TSK-1800: add secondary object references

common/taskana-common-data/src/main/resources/sql/sample-data/object-reference.sql

@@ -1,3 +1,4 @@
-INSERT INTO OBJECT_REFERENCE VALUES ('1', 'Company1', 'System1', 'Instance1', 'Type1', 'Value1');
+INSERT INTO OBJECT_REFERENCE VALUES ('ID1', 'TKI:000000000000000000000000000000000000', 'Company1', 'System1', 'Instance1', 'Type1', 'Value1');
-INSERT INTO OBJECT_REFERENCE VALUES ('2', 'Company2', 'System2', 'Instance2', 'Type2', 'Value2');
+INSERT INTO OBJECT_REFERENCE VALUES ('ID2', 'TKI:000000000000000000000000000000000000', 'Company2', 'System2', 'Instance2', 'Type2', 'Value2');
-INSERT INTO OBJECT_REFERENCE VALUES ('3', 'Company3', 'System3', 'Instance3', 'Type3', 'Value3');
+INSERT INTO OBJECT_REFERENCE VALUES ('ID3', 'TKI:000000000000000000000000000000000001', 'Company3', 'System3', 'Instance3', 'Type3', 'Value2');
+INSERT INTO OBJECT_REFERENCE VALUES ('ID4', 'TKI:000000000000000000000000000000000002', 'Company1', 'System4', 'Instance4', 'Type2', 'Value2');

common/taskana-common-data/src/main/resources/sql/test-data/object-reference.sql

@@ -1,3 +1,3 @@
-INSERT INTO OBJECT_REFERENCE VALUES ('1', 'Company1', 'System1', 'Instance1', 'Type1', 'Value1');
+INSERT INTO OBJECT_REFERENCE VALUES ('1', 'TaskId1', 'Company1', 'System1', 'Instance1', 'Type1', 'Value1');
-INSERT INTO OBJECT_REFERENCE VALUES ('2', 'Company2', 'System2', 'Instance2', 'Type2', 'Value2');
+INSERT INTO OBJECT_REFERENCE VALUES ('2', 'TaskId2', 'Company2', 'System2', 'Instance2', 'Type2', 'Value2');
-INSERT INTO OBJECT_REFERENCE VALUES ('3', 'Company3', 'System3', 'Instance3', 'Type3', 'Value3');
+INSERT INTO OBJECT_REFERENCE VALUES ('3', 'TaskId3', 'Company3', 'System3', 'Instance3', 'Type3', 'Value3');

common/taskana-common/src/main/java/pro/taskana/common/internal/util/IdGenerator.java

@@ -14,6 +14,7 @@ public final class IdGenerator {
   public static final String ID_PREFIX_EXT_TASK = "ETI";
   public static final String ID_PREFIX_BUSINESS_PROCESS = "BPI";
   public static final String ID_PREFIX_ATTACHMENT = "TAI";
+  public static final String ID_PREFIX_OBJECT_REFERENCE = "ORI";
 
   public static final String ID_PREFIX_TASK_COMMENT = "TCI";
 

common/taskana-common/src/main/resources/sql/db2/taskana-schema-db2.sql

@@ -1,15 +1,18 @@
 SET SCHEMA %schemaName%;
 
-CREATE TABLE TASKANA_SCHEMA_VERSION(
+CREATE TABLE TASKANA_SCHEMA_VERSION
+(
     ID      INT          NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),
     VERSION VARCHAR(255) NOT NULL,
     CREATED TIMESTAMP    NOT NULL,
     PRIMARY KEY (ID)
 );
 -- The VERSION value must match the value of TaskanaEngineConfiguration.TASKANA_SCHEMA_VERSION
-INSERT INTO TASKANA_SCHEMA_VERSION (VERSION, CREATED) VALUES ('5.0.0', CURRENT_TIMESTAMP);
+INSERT INTO TASKANA_SCHEMA_VERSION (VERSION, CREATED)
+VALUES ('5.0.0', CURRENT_TIMESTAMP);
 
-CREATE TABLE CLASSIFICATION(
+CREATE TABLE CLASSIFICATION
+(
     ID                      VARCHAR(40) NOT NULL,
     KEY                     VARCHAR(32) NOT NULL,
     PARENT_ID               VARCHAR(40) NOT NULL,
@@ -37,7 +40,8 @@ CREATE TABLE CLASSIFICATION(
     CONSTRAINT UC_CLASS_KEY_DOMAIN UNIQUE (KEY, DOMAIN)
 );
 
-CREATE TABLE WORKBASKET(
+CREATE TABLE WORKBASKET
+(
     ID                  VARCHAR(40)  NOT NULL,
     KEY                 VARCHAR(64)  NOT NULL,
     CREATED             TIMESTAMP NULL,
@@ -60,7 +64,8 @@ CREATE TABLE WORKBASKET(
     CONSTRAINT WB_KEY_DOMAIN UNIQUE (KEY, DOMAIN)
 );
 
-CREATE TABLE TASK (
+CREATE TABLE TASK
+(
     ID                         VARCHAR(40)  NOT NULL,
     EXTERNAL_ID                VARCHAR(64)  NOT NULL,
     CREATED                    TIMESTAMP NULL,
@@ -126,13 +131,15 @@ CREATE TABLE TASK (
     CONSTRAINT TASK_CLASS FOREIGN KEY (CLASSIFICATION_ID) REFERENCES CLASSIFICATION ON DELETE NO ACTION
 );
 
-CREATE TABLE DISTRIBUTION_TARGETS(
+CREATE TABLE DISTRIBUTION_TARGETS
+(
     SOURCE_ID VARCHAR(40) NOT NULL,
     TARGET_ID VARCHAR(40) NOT NULL,
     PRIMARY KEY (SOURCE_ID, TARGET_ID)
 );
 
-CREATE TABLE WORKBASKET_ACCESS_LIST(
+CREATE TABLE WORKBASKET_ACCESS_LIST
+(
     ID              VARCHAR(40)  NOT NULL,
     WORKBASKET_ID   VARCHAR(40)  NOT NULL,
     ACCESS_ID       VARCHAR(255) NOT NULL,
@@ -159,8 +166,10 @@ CREATE TABLE WORKBASKET_ACCESS_LIST(
     CONSTRAINT ACCESS_LIST_WB FOREIGN KEY (WORKBASKET_ID) REFERENCES WORKBASKET ON DELETE CASCADE
 );
 
-CREATE TABLE OBJECT_REFERENCE(
+CREATE TABLE OBJECT_REFERENCE
+(
     ID              VARCHAR(40)  NOT NULL,
+    TASK_ID         VARCHAR(40)  NOT NULL,
     COMPANY         VARCHAR(32)  NOT NULL,
     SYSTEM          VARCHAR(32),
     SYSTEM_INSTANCE VARCHAR(32),
@@ -168,7 +177,8 @@ CREATE TABLE OBJECT_REFERENCE(
     VALUE           VARCHAR(128) NOT NULL
 );
 
-CREATE TABLE ATTACHMENT(
+CREATE TABLE ATTACHMENT
+(
     ID                 VARCHAR(40)  NOT NULL,
     TASK_ID            VARCHAR(40)  NOT NULL,
     CREATED            TIMESTAMP NULL,
@@ -187,16 +197,19 @@ CREATE TABLE ATTACHMENT(
     CONSTRAINT ATT_CLASS FOREIGN KEY (CLASSIFICATION_ID) REFERENCES CLASSIFICATION ON DELETE NO ACTION
 );
 
-CREATE TABLE CONFIGURATION (
+CREATE TABLE CONFIGURATION
+(
     NAME              VARCHAR(8) NOT NULL,
     ENFORCE_SECURITY  BOOLEAN NULL,
     CUSTOM_ATTRIBUTES CLOB NULL,
     PRIMARY KEY (NAME)
 );
 
-INSERT INTO CONFIGURATION (NAME) VALUES ('MASTER');
+INSERT INTO CONFIGURATION (NAME)
+VALUES ('MASTER');
 
-CREATE TABLE TASK_COMMENT(
+CREATE TABLE TASK_COMMENT
+(
     ID         VARCHAR(40) NOT NULL,
     TASK_ID    VARCHAR(40) NOT NULL,
     TEXT_FIELD VARCHAR(1024) NULL,
@@ -207,7 +220,8 @@ CREATE TABLE TASK_COMMENT(
     CONSTRAINT COMMENT_TASK FOREIGN KEY (TASK_ID) REFERENCES TASK ON DELETE CASCADE
 );
 
-CREATE TABLE SCHEDULED_JOB(
+CREATE TABLE SCHEDULED_JOB
+(
     JOB_ID       INTEGER NOT NULL,
     PRIORITY     INTEGER NULL,
     CREATED      TIMESTAMP NULL,
@@ -221,7 +235,8 @@ CREATE TABLE SCHEDULED_JOB(
     PRIMARY KEY (JOB_ID)
 );
 
-CREATE TABLE TASK_HISTORY_EVENT (
+CREATE TABLE TASK_HISTORY_EVENT
+(
     ID                             VARCHAR(40) NOT NULL,
     BUSINESS_PROCESS_ID            VARCHAR(128) NULL,
     PARENT_BUSINESS_PROCESS_ID     VARCHAR(128) NULL,
@@ -309,7 +324,8 @@ CREATE TABLE CLASSIFICATION_HISTORY_EVENT
 );
 
 -- USER can not be taken as table name because it is a reserved keyword.
-CREATE TABLE USER_INFO (
+CREATE TABLE USER_INFO
+(
     USER_ID      VARCHAR(32) NOT NULL,
     FIRST_NAME   VARCHAR(32) NULL,
     LASTNAME     VARCHAR(32) NULL,
@@ -330,8 +346,7 @@ CREATE TABLE USER_INFO (
 CREATE SEQUENCE SCHEDULED_JOB_SEQ
     MINVALUE 1
     START WITH 1
-  INCREMENT BY 1
+    INCREMENT BY 1 CACHE 10;
-  CACHE 10;
 
 
 -- LIST OF RECOMMENDED INDEXES
@@ -339,76 +354,67 @@ CREATE SEQUENCE SCHEDULED_JOB_SEQ
 -- The script needs to be reviewed and adapted for each indiviual TASKANA setup.
 -- ===========================
 CREATE UNIQUE INDEX IDX_CLASSIFICATION_ID ON CLASSIFICATION
-   ("ID" ASC)
+    ("ID" ASC) INCLUDE ("CUSTOM_8", "CUSTOM_7", "CUSTOM_6", "CUSTOM_5", "CUSTOM_4", "CUSTOM_3", "CUSTOM_2",
-   INCLUDE ("CUSTOM_8", "CUSTOM_7", "CUSTOM_6", "CUSTOM_5", "CUSTOM_4", "CUSTOM_3", "CUSTOM_2",
    "CUSTOM_1", "APPLICATION_ENTRY_POINT", "SERVICE_LEVEL", "PRIORITY", "DESCRIPTION", "NAME",
    "CREATED", "VALID_IN_DOMAIN", "DOMAIN", "TYPE", "CATEGORY", "PARENT_KEY", "PARENT_ID", "KEY")
    ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-COMMIT WORK ;
+COMMIT WORK;
 
 CREATE INDEX IDX_CLASSIFICATION_CATEGORY ON CLASSIFICATION
     ("CATEGORY" ASC, "DOMAIN" ASC, "TYPE" ASC, "CUSTOM_1" ASC, "CUSTOM_8" ASC, "CUSTOM_7" ASC,
      "CUSTOM_6" ASC, "CUSTOM_5" ASC, "CUSTOM_4" ASC, "CUSTOM_3" ASC, "CUSTOM_2" ASC,
      "APPLICATION_ENTRY_POINT" ASC, "SERVICE_LEVEL" ASC, "PRIORITY" ASC, "DESCRIPTION" ASC,
      "NAME" ASC, "CREATED" ASC, "VALID_IN_DOMAIN" ASC, "PARENT_KEY" ASC, "PARENT_ID" ASC, "KEY" ASC,
-   "ID" ASC)
+     "ID" ASC) ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-   ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
+COMMIT WORK;
-COMMIT WORK ;
 
 CREATE UNIQUE INDEX IDX_CLASSIFICATION_KEY_DOMAIN ON CLASSIFICATION
-   ("KEY" ASC, "DOMAIN" ASC)
+    ("KEY" ASC, "DOMAIN" ASC) INCLUDE ("CUSTOM_8", "CUSTOM_7", "CUSTOM_6", "CUSTOM_5", "CUSTOM_4", "CUSTOM_3", "CUSTOM_2",
-   INCLUDE ("CUSTOM_8", "CUSTOM_7", "CUSTOM_6", "CUSTOM_5", "CUSTOM_4", "CUSTOM_3", "CUSTOM_2",
    "CUSTOM_1", "APPLICATION_ENTRY_POINT", "SERVICE_LEVEL", "PRIORITY", "DESCRIPTION", "NAME",
    "CREATED", "VALID_IN_DOMAIN", "TYPE", "CATEGORY", "PARENT_KEY", "PARENT_ID", "ID")
    ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-COMMIT WORK ;
+COMMIT WORK;
 
 CREATE INDEX IDX_TASK_WORKBASKET_KEY_DOMAIN ON TASK
-   ("WORKBASKET_KEY" ASC, "DOMAIN" DESC)
+    ("WORKBASKET_KEY" ASC, "DOMAIN" DESC) ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-   ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
+COMMIT WORK;
-COMMIT WORK ;
 
 CREATE INDEX IDX_TASK_POR_VALUE ON TASK
-   (UPPER("POR_VALUE") ASC, "WORKBASKET_ID" ASC)
+    (UPPER("POR_VALUE") ASC, "WORKBASKET_ID" ASC) ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-   ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
+COMMIT WORK;
-COMMIT WORK ;
 
 CREATE INDEX IDX_ATTACHMENT_TASK_ID ON ATTACHMENT
     ("TASK_ID" ASC, "RECEIVED" ASC, "CLASSIFICATION_ID" ASC, "CLASSIFICATION_KEY" ASC,
-   "MODIFIED" ASC, "CREATED" ASC, "ID" ASC)
+     "MODIFIED" ASC, "CREATED" ASC, "ID"
-   ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
+     ASC) ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-COMMIT WORK ;
+COMMIT WORK;
 
 CREATE UNIQUE INDEX IDX_WORKBASKET_ID ON WORKBASKET
-   ("ID" ASC)
+    ("ID" ASC) INCLUDE ("ORG_LEVEL_4", "ORG_LEVEL_3", "ORG_LEVEL_2", "ORG_LEVEL_1", "OWNER", "DESCRIPTION",
-   INCLUDE ("ORG_LEVEL_4", "ORG_LEVEL_3", "ORG_LEVEL_2", "ORG_LEVEL_1", "OWNER", "DESCRIPTION",
    "TYPE", "DOMAIN", "NAME", "KEY")
    ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-COMMIT WORK ;
+COMMIT WORK;
 
 CREATE UNIQUE INDEX IDX_WORKBASKET_KEY_DOMAIN ON WORKBASKET
-   ("KEY" ASC, "DOMAIN" ASC)
+    ("KEY" ASC, "DOMAIN" ASC) INCLUDE ("ORG_LEVEL_4", "ORG_LEVEL_3", "ORG_LEVEL_2", "ORG_LEVEL_1", "CUSTOM_4", "CUSTOM_3",
-   INCLUDE ("ORG_LEVEL_4", "ORG_LEVEL_3", "ORG_LEVEL_2", "ORG_LEVEL_1", "CUSTOM_4", "CUSTOM_3",
    "CUSTOM_2", "CUSTOM_1", "OWNER", "DESCRIPTION", "TYPE", "NAME", "MODIFIED", "CREATED", "ID")
    ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-COMMIT WORK ;
+COMMIT WORK;
 
 CREATE UNIQUE INDEX IDX_WORKBASKET_KEY_DOMAIN_ID ON WORKBASKET
-   ("KEY" ASC, "DOMAIN" ASC)
+    ("KEY" ASC, "DOMAIN" ASC) INCLUDE ("ID")
-   INCLUDE ("ID")
    ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-COMMIT WORK ;
+COMMIT WORK;
 
 CREATE INDEX IDX_WORKBASKET_ACCESS_LIST_ACCESS_ID ON WORKBASKET_ACCESS_LIST
-   ("ACCESS_ID" ASC, "WORKBASKET_ID" ASC, "PERM_READ" ASC)
+    ("ACCESS_ID" ASC, "WORKBASKET_ID" ASC, "PERM_READ" ASC) ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
-   ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
+COMMIT WORK;
-COMMIT WORK ;
 
 CREATE INDEX IDX_WORKBASKET_ACCESS_LIST_WORKBASKET_ID ON WORKBASKET_ACCESS_LIST
     ("WORKBASKET_ID" ASC, "PERM_CUSTOM_12" ASC, "PERM_CUSTOM_11" ASC, "PERM_CUSTOM_10" ASC,
      "PERM_CUSTOM_9" ASC, "PERM_CUSTOM_8" ASC, "PERM_CUSTOM_7" ASC, "PERM_CUSTOM_6" ASC,
      "PERM_CUSTOM_5" ASC, "PERM_CUSTOM_4" ASC, "PERM_CUSTOM_3" ASC, "PERM_CUSTOM_2" ASC,
      "PERM_CUSTOM_1" ASC, "PERM_DISTRIBUTE" ASC, "PERM_TRANSFER" ASC, "PERM_APPEND" ASC,
-   "PERM_OPEN" ASC, "PERM_READ" ASC, "ACCESS_ID" ASC)
+     "PERM_OPEN" ASC, "PERM_READ" ASC, "ACCESS_ID"
-   ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
+     ASC) ALLOW REVERSE SCANS COLLECT SAMPLED DETAILED STATISTICS;
- COMMIT WORK ;
+COMMIT WORK;

common/taskana-common/src/main/resources/sql/db2/taskana_schema_update_4.11.0_to_5.0.0_db2.sql

@@ -4,6 +4,8 @@ SET SCHEMA %schemaName%;
 
 INSERT INTO TASKANA_SCHEMA_VERSION (VERSION, CREATED) VALUES ('5.0.0', CURRENT_TIMESTAMP);
 
+ALTER TABLE OBJECT_REFERENCE ADD COLUMN TASK_ID VARCHAR(40) NOT NULL DEFAULT 'EMPTY';
+
 DROP INDEX "DB2ADMIN"."IDX1805212017540";
 DROP INDEX "DB2ADMIN"."IDX1805212018000";
 DROP INDEX "DB2ADMIN"."IDX1805212018030";

common/taskana-common/src/main/resources/sql/h2/taskana-schema-h2.sql

@@ -7,16 +7,19 @@ SET SCHEMA %schemaName%;
 -- here in this file!
 -- SET COLLATION DEFAULT_de_DE;
 
-CREATE TABLE TASKANA_SCHEMA_VERSION(
+CREATE TABLE TASKANA_SCHEMA_VERSION
+(
     ID      INT          NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1 INCREMENT BY 1),
     VERSION VARCHAR(255) NOT NULL,
     CREATED TIMESTAMP    NOT NULL,
     PRIMARY KEY (ID)
 );
 -- The VERSION value must match the value of TaskanaEngineConfiguration.TASKANA_SCHEMA_VERSION
-INSERT INTO TASKANA_SCHEMA_VERSION (VERSION, CREATED) VALUES ('5.0.0', CURRENT_TIMESTAMP);
+INSERT INTO TASKANA_SCHEMA_VERSION (VERSION, CREATED)
+VALUES ('5.0.0', CURRENT_TIMESTAMP);
 
-CREATE TABLE CLASSIFICATION(
+CREATE TABLE CLASSIFICATION
+(
     ID                      VARCHAR(40) NOT NULL,
     KEY                     VARCHAR(32) NOT NULL,
     PARENT_ID               VARCHAR(40) NOT NULL,
@@ -44,7 +47,8 @@ CREATE TABLE CLASSIFICATION(
     CONSTRAINT UC_CLASS_KEY_DOMAIN UNIQUE (KEY, DOMAIN)
 );
 
-CREATE TABLE WORKBASKET(
+CREATE TABLE WORKBASKET
+(
     ID                  VARCHAR(40)  NOT NULL,
     KEY                 VARCHAR(64)  NOT NULL,
     CREATED             TIMESTAMP NULL,
@@ -67,7 +71,8 @@ CREATE TABLE WORKBASKET(
     CONSTRAINT WB_KEY_DOMAIN UNIQUE (KEY, DOMAIN)
 );
 
-CREATE TABLE TASK (
+CREATE TABLE TASK
+(
     ID                         VARCHAR(40)  NOT NULL,
     EXTERNAL_ID                VARCHAR(64)  NOT NULL,
     CREATED                    TIMESTAMP NULL,
@@ -133,13 +138,15 @@ CREATE TABLE TASK (
     CONSTRAINT TASK_CLASS FOREIGN KEY (CLASSIFICATION_ID) REFERENCES CLASSIFICATION ON DELETE NO ACTION
 );
 
-CREATE TABLE DISTRIBUTION_TARGETS(
+CREATE TABLE DISTRIBUTION_TARGETS
+(
     SOURCE_ID VARCHAR(40) NOT NULL,
     TARGET_ID VARCHAR(40) NOT NULL,
     PRIMARY KEY (SOURCE_ID, TARGET_ID)
 );
 
-CREATE TABLE WORKBASKET_ACCESS_LIST(
+CREATE TABLE WORKBASKET_ACCESS_LIST
+(
     ID              VARCHAR(40)  NOT NULL,
     WORKBASKET_ID   VARCHAR(40)  NOT NULL,
     ACCESS_ID       VARCHAR(255) NOT NULL,
@@ -166,8 +173,10 @@ CREATE TABLE WORKBASKET_ACCESS_LIST(
     CONSTRAINT ACCESS_LIST_WB FOREIGN KEY (WORKBASKET_ID) REFERENCES WORKBASKET ON DELETE CASCADE
 );
 
-CREATE TABLE OBJECT_REFERENCE(
+CREATE TABLE OBJECT_REFERENCE
+(
     ID              VARCHAR(40)  NOT NULL,
+    TASK_ID         VARCHAR(40)  NOT NULL,
     COMPANY         VARCHAR(32)  NOT NULL,
     SYSTEM          VARCHAR(32),
     SYSTEM_INSTANCE VARCHAR(32),
@@ -175,7 +184,8 @@ CREATE TABLE OBJECT_REFERENCE(
     VALUE           VARCHAR(128) NOT NULL
 );
 
-CREATE TABLE ATTACHMENT(
+CREATE TABLE ATTACHMENT
+(
     ID                 VARCHAR(40)  NOT NULL,
     TASK_ID            VARCHAR(40)  NOT NULL,
     CREATED            TIMESTAMP NULL,
@@ -194,7 +204,8 @@ CREATE TABLE ATTACHMENT(
     CONSTRAINT ATT_CLASS FOREIGN KEY (CLASSIFICATION_ID) REFERENCES CLASSIFICATION ON DELETE NO ACTION
 );
 
-CREATE TABLE TASK_COMMENT(
+CREATE TABLE TASK_COMMENT
+(
     ID         VARCHAR(40) NOT NULL,
     TASK_ID    VARCHAR(40) NOT NULL,
     TEXT_FIELD VARCHAR(1024) NULL,
@@ -205,7 +216,8 @@ CREATE TABLE TASK_COMMENT(
     CONSTRAINT COMMENT_TASK FOREIGN KEY (TASK_ID) REFERENCES TASK ON DELETE CASCADE
 );
 
-CREATE TABLE SCHEDULED_JOB(
+CREATE TABLE SCHEDULED_JOB
+(
     JOB_ID       INTEGER NOT NULL,
     PRIORITY     INTEGER NULL,
     CREATED      TIMESTAMP NULL,
@@ -219,7 +231,8 @@ CREATE TABLE SCHEDULED_JOB(
     PRIMARY KEY (JOB_ID)
 );
 
-CREATE TABLE TASK_HISTORY_EVENT (
+CREATE TABLE TASK_HISTORY_EVENT
+(
     ID                             VARCHAR(40) NOT NULL,
     BUSINESS_PROCESS_ID            VARCHAR(128) NULL,
     PARENT_BUSINESS_PROCESS_ID     VARCHAR(128) NULL,
@@ -306,16 +319,19 @@ CREATE TABLE CLASSIFICATION_HISTORY_EVENT
     PRIMARY KEY (ID)
 );
 
-CREATE TABLE CONFIGURATION (
+CREATE TABLE CONFIGURATION
+(
     NAME              VARCHAR(8) NOT NULL,
     ENFORCE_SECURITY  BOOLEAN NULL,
     CUSTOM_ATTRIBUTES CLOB NULL,
     PRIMARY KEY (NAME)
 );
 
-INSERT INTO CONFIGURATION (NAME) VALUES ('MASTER');
+INSERT INTO CONFIGURATION (NAME)
+VALUES ('MASTER');
 
-CREATE TABLE USER_INFO (
+CREATE TABLE USER_INFO
+(
     USER_ID      VARCHAR(32) NOT NULL,
     FIRST_NAME   VARCHAR(32) NULL,
     LASTNAME     VARCHAR(32) NULL,
@@ -336,6 +352,5 @@ CREATE TABLE USER_INFO (
 CREATE SEQUENCE SCHEDULED_JOB_SEQ
     MINVALUE 1
     START WITH 1
-  INCREMENT BY 1
+    INCREMENT BY 1 CACHE 10;
-  CACHE 10;
 

common/taskana-common/src/main/resources/sql/h2/taskana_schema_update_4.11.0_to_5.0.0_h2.sql

@@ -2,4 +2,4 @@
 
 INSERT INTO TASKANA_SCHEMA_VERSION (VERSION, CREATED) VALUES ('5.0.0', CURRENT_TIMESTAMP);
 
-
+ALTER TABLE OBJECT_REFERENCE ADD COLUMN TASK_ID VARCHAR(40) NOT NULL DEFAULT 'EMPTY';

common/taskana-common/src/main/resources/sql/postgres/taskana-schema-postgres.sql

@@ -1,17 +1,21 @@
 CREATE SCHEMA IF NOT EXISTS %schemaName%;
 
-SET search_path TO %schemaName%;
+SET
+search_path TO %schemaName%;
 
-CREATE TABLE TASKANA_SCHEMA_VERSION(
+CREATE TABLE TASKANA_SCHEMA_VERSION
+(
     ID      INT          NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1 INCREMENT BY 1),
     VERSION VARCHAR(255) NOT NULL,
     CREATED TIMESTAMP    NOT NULL,
     PRIMARY KEY (ID)
 );
 -- The VERSION value must match the value of TaskanaEngineConfiguration.TASKANA_SCHEMA_VERSION
-INSERT INTO TASKANA_SCHEMA_VERSION (VERSION, CREATED) VALUES ('5.0.0', CURRENT_TIMESTAMP);
+INSERT INTO TASKANA_SCHEMA_VERSION (VERSION, CREATED)
+VALUES ('5.0.0', CURRENT_TIMESTAMP);
 
-CREATE TABLE CLASSIFICATION(
+CREATE TABLE CLASSIFICATION
+(
     ID                      VARCHAR(40) NOT NULL,
     KEY                     VARCHAR(32) NOT NULL,
     PARENT_ID               VARCHAR(40) NOT NULL,
@@ -39,7 +43,8 @@ CREATE TABLE CLASSIFICATION(
     CONSTRAINT UC_CLASS_KEY_DOMAIN UNIQUE (KEY, DOMAIN)
 );
 
-CREATE TABLE WORKBASKET(
+CREATE TABLE WORKBASKET
+(
     ID                  VARCHAR(40)  NOT NULL,
     KEY                 VARCHAR(64)  NOT NULL,
     CREATED             TIMESTAMP NULL,
@@ -62,7 +67,8 @@ CREATE TABLE WORKBASKET(
     CONSTRAINT WB_KEY_DOMAIN UNIQUE (KEY, DOMAIN)
 );
 
-CREATE TABLE TASK (
+CREATE TABLE TASK
+(
     ID                         VARCHAR(40)  NOT NULL,
     EXTERNAL_ID                VARCHAR(64)  NOT NULL,
     CREATED                    TIMESTAMP NULL,
@@ -128,13 +134,15 @@ CREATE TABLE TASK (
     CONSTRAINT TASK_CLASS FOREIGN KEY (CLASSIFICATION_ID) REFERENCES CLASSIFICATION ON DELETE NO ACTION
 );
 
-CREATE TABLE DISTRIBUTION_TARGETS(
+CREATE TABLE DISTRIBUTION_TARGETS
+(
     SOURCE_ID VARCHAR(40) NOT NULL,
     TARGET_ID VARCHAR(40) NOT NULL,
     PRIMARY KEY (SOURCE_ID, TARGET_ID)
 );
 
-CREATE TABLE WORKBASKET_ACCESS_LIST(
+CREATE TABLE WORKBASKET_ACCESS_LIST
+(
     ID              VARCHAR(40)  NOT NULL,
     WORKBASKET_ID   VARCHAR(40)  NOT NULL,
     ACCESS_ID       VARCHAR(255) NOT NULL,
@@ -161,8 +169,10 @@ CREATE TABLE WORKBASKET_ACCESS_LIST(
     CONSTRAINT ACCESS_LIST_WB FOREIGN KEY (WORKBASKET_ID) REFERENCES WORKBASKET ON DELETE CASCADE
 );
 
-CREATE TABLE OBJECT_REFERENCE(
+CREATE TABLE OBJECT_REFERENCE
+(
     ID              VARCHAR(40)  NOT NULL,
+    TASK_ID         VARCHAR(40)  NOT NULL,
     COMPANY         VARCHAR(32)  NOT NULL,
     SYSTEM          VARCHAR(32),
     SYSTEM_INSTANCE VARCHAR(32),
@@ -170,7 +180,8 @@ CREATE TABLE OBJECT_REFERENCE(
     VALUE           VARCHAR(128) NOT NULL
 );
 
-CREATE TABLE ATTACHMENT(
+CREATE TABLE ATTACHMENT
+(
     ID                 VARCHAR(40)  NOT NULL,
     TASK_ID            VARCHAR(40)  NOT NULL,
     CREATED            TIMESTAMP NULL,
@@ -189,7 +200,8 @@ CREATE TABLE ATTACHMENT(
     CONSTRAINT ATT_CLASS FOREIGN KEY (CLASSIFICATION_ID) REFERENCES CLASSIFICATION ON DELETE NO ACTION
 );
 
-CREATE TABLE TASK_COMMENT(
+CREATE TABLE TASK_COMMENT
+(
     ID         VARCHAR(40) NOT NULL,
     TASK_ID    VARCHAR(40) NOT NULL,
     TEXT_FIELD VARCHAR(1024) NULL,
@@ -200,7 +212,8 @@ CREATE TABLE TASK_COMMENT(
     CONSTRAINT COMMENT_TASK FOREIGN KEY (TASK_ID) REFERENCES TASK ON DELETE CASCADE
 );
 
-CREATE TABLE SCHEDULED_JOB(
+CREATE TABLE SCHEDULED_JOB
+(
     JOB_ID       INTEGER NOT NULL,
     PRIORITY     INTEGER NULL,
     CREATED      TIMESTAMP NULL,
@@ -214,7 +227,8 @@ CREATE TABLE SCHEDULED_JOB(
     PRIMARY KEY (JOB_ID)
 );
 
-CREATE TABLE TASK_HISTORY_EVENT (
+CREATE TABLE TASK_HISTORY_EVENT
+(
     ID                             VARCHAR(40) NOT NULL,
     BUSINESS_PROCESS_ID            VARCHAR(128) NULL,
     PARENT_BUSINESS_PROCESS_ID     VARCHAR(128) NULL,
@@ -301,17 +315,20 @@ CREATE TABLE CLASSIFICATION_HISTORY_EVENT
     PRIMARY KEY (ID)
 );
 
-CREATE TABLE CONFIGURATION (
+CREATE TABLE CONFIGURATION
+(
     NAME              VARCHAR(8) NOT NULL,
     ENFORCE_SECURITY  BOOLEAN NULL,
     CUSTOM_ATTRIBUTES TEXT NULL,
     PRIMARY KEY (NAME)
 );
 
-INSERT INTO CONFIGURATION (NAME) VALUES ('MASTER');
+INSERT INTO CONFIGURATION (NAME)
+VALUES ('MASTER');
 
 
-CREATE TABLE USER_INFO (
+CREATE TABLE USER_INFO
+(
     USER_ID      VARCHAR(32) NOT NULL,
     FIRST_NAME   VARCHAR(32) NULL,
     LASTNAME     VARCHAR(32) NULL,
@@ -332,19 +349,19 @@ CREATE TABLE USER_INFO (
 CREATE SEQUENCE SCHEDULED_JOB_SEQ
     MINVALUE 1
     START WITH 1
-  INCREMENT BY 1
+    INCREMENT BY 1 CACHE 10;
-  CACHE 10;
 
- SET search_path TO taskana;
+SET
+search_path TO taskana;
 
- CREATE INDEX IDX_CLASSIFICATION_ID ON CLASSIFICATION
+CREATE INDEX IDX_CLASSIFICATION_ID ON CLASSIFICATION
     (ID ASC, CUSTOM_8, CUSTOM_7, CUSTOM_6, CUSTOM_5, CUSTOM_4,
      CUSTOM_3, CUSTOM_2, CUSTOM_1, APPLICATION_ENTRY_POINT,
      SERVICE_LEVEL, PRIORITY, DESCRIPTION, NAME, MODIFIED,
      CREATED, VALID_IN_DOMAIN, DOMAIN, TYPE, CATEGORY, PARENT_KEY,
      PARENT_ID, KEY);
-   COMMIT WORK ;
+COMMIT WORK;
- CREATE INDEX IDX_CLASSIFICATION_CATEGORY ON CLASSIFICATION
+CREATE INDEX IDX_CLASSIFICATION_CATEGORY ON CLASSIFICATION
     (CATEGORY ASC, DOMAIN ASC, TYPE ASC, CUSTOM_1
      ASC, CUSTOM_8 ASC, CUSTOM_7 ASC, CUSTOM_6 ASC,
      CUSTOM_5 ASC, CUSTOM_4 ASC, CUSTOM_3 ASC, CUSTOM_2
@@ -352,56 +369,56 @@ CREATE SEQUENCE SCHEDULED_JOB_SEQ
      ASC, PRIORITY ASC, DESCRIPTION ASC, NAME ASC,
      CREATED ASC, VALID_IN_DOMAIN ASC, PARENT_KEY ASC, PARENT_ID
      ASC, KEY ASC, ID ASC);
-   COMMIT WORK ;
+COMMIT WORK;
- CREATE INDEX IDX_CLASSIFICATION_KEY_DOMAIN ON CLASSIFICATION
+CREATE INDEX IDX_CLASSIFICATION_KEY_DOMAIN ON CLASSIFICATION
     (KEY ASC, DOMAIN ASC, CUSTOM_8, CUSTOM_7, CUSTOM_6,
      CUSTOM_5, CUSTOM_4, CUSTOM_3, CUSTOM_2, CUSTOM_1,
      APPLICATION_ENTRY_POINT, SERVICE_LEVEL, PRIORITY,
      DESCRIPTION, NAME, CREATED, VALID_IN_DOMAIN,
-   TYPE, CATEGORY, PARENT_KEY, PARENT_ID, ID) ;
+     TYPE, CATEGORY, PARENT_KEY, PARENT_ID, ID);
-   COMMIT WORK ;
+COMMIT WORK;
 
 
- CREATE INDEX IDX_TASK_WORKBASKET_KEY_DOMAIN ON TASK
+CREATE INDEX IDX_TASK_WORKBASKET_KEY_DOMAIN ON TASK
     (WORKBASKET_KEY ASC, DOMAIN DESC);
-   COMMIT WORK ;
+COMMIT WORK;
- CREATE INDEX IDX_TASK_POR_VALUE ON TASK
+CREATE INDEX IDX_TASK_POR_VALUE ON TASK
     (UPPER(POR_VALUE) ASC, WORKBASKET_ID ASC);
-   COMMIT WORK ;
+COMMIT WORK;
 
 
- CREATE INDEX IDX_ATTACHMENT_TASK_ID ON ATTACHMENT
+CREATE INDEX IDX_ATTACHMENT_TASK_ID ON ATTACHMENT
     (TASK_ID ASC, RECEIVED ASC, CLASSIFICATION_ID
      ASC, CLASSIFICATION_KEY ASC, MODIFIED ASC, CREATED
-   ASC, ID ASC) ;
+     ASC, ID ASC);
-   COMMIT WORK ;
+COMMIT WORK;
 
 
- CREATE INDEX IDX_WORKBASKET_ID ON WORKBASKET
+CREATE INDEX IDX_WORKBASKET_ID ON WORKBASKET
     (ID ASC, ORG_LEVEL_4, ORG_LEVEL_3, ORG_LEVEL_2,
      ORG_LEVEL_1, OWNER, DESCRIPTION, TYPE, DOMAIN, NAME, KEY);
-   COMMIT WORK ;
+COMMIT WORK;
- CREATE INDEX IDX_WORKBASKET_KEY_DOMAIN ON WORKBASKET
+CREATE INDEX IDX_WORKBASKET_KEY_DOMAIN ON WORKBASKET
     (KEY ASC, DOMAIN ASC, ORG_LEVEL_4,
      ORG_LEVEL_3, ORG_LEVEL_2, ORG_LEVEL_1, CUSTOM_4,
      CUSTOM_3, CUSTOM_2, CUSTOM_1, OWNER, DESCRIPTION,
-   TYPE, NAME, MODIFIED, CREATED, ID) ;
+     TYPE, NAME, MODIFIED, CREATED, ID);
-   COMMIT WORK ;
+COMMIT WORK;
-  CREATE INDEX IDX_WORKBASKET_KEY_DOMAIN_ID ON WORKBASKET
+CREATE INDEX IDX_WORKBASKET_KEY_DOMAIN_ID ON WORKBASKET
-   (KEY ASC, DOMAIN ASC, ID) ;
+    (KEY ASC, DOMAIN ASC, ID);
-   COMMIT WORK ;
+COMMIT WORK;
 
 
- CREATE INDEX IDX_WORKBASKET_ACCESS_LIST_ACCESS_ID ON WORKBASKET_ACCESS_LIST
+CREATE INDEX IDX_WORKBASKET_ACCESS_LIST_ACCESS_ID ON WORKBASKET_ACCESS_LIST
-   (ACCESS_ID ASC, WORKBASKET_ID ASC, PERM_READ ASC) ;
+    (ACCESS_ID ASC, WORKBASKET_ID ASC, PERM_READ ASC);
-   COMMIT WORK ;
+COMMIT WORK;
- CREATE INDEX IDX_WORKBASKET_ACCESS_LIST_WORKBASKET_ID ON WORKBASKET_ACCESS_LIST
+CREATE INDEX IDX_WORKBASKET_ACCESS_LIST_WORKBASKET_ID ON WORKBASKET_ACCESS_LIST
     (WORKBASKET_ID ASC, PERM_CUSTOM_12 ASC, PERM_CUSTOM_11
      ASC, PERM_CUSTOM_10 ASC, PERM_CUSTOM_9 ASC, PERM_CUSTOM_8
      ASC, PERM_CUSTOM_7 ASC, PERM_CUSTOM_6 ASC, PERM_CUSTOM_5
      ASC, PERM_CUSTOM_4 ASC, PERM_CUSTOM_3 ASC, PERM_CUSTOM_2
      ASC, PERM_CUSTOM_1 ASC, PERM_DISTRIBUTE ASC, PERM_TRANSFER
      ASC, PERM_APPEND ASC, PERM_OPEN ASC, PERM_READ
-   ASC, ACCESS_ID ASC) ;
+     ASC, ACCESS_ID ASC);
-   COMMIT WORK ;
+COMMIT WORK;
 

common/taskana-common/src/main/resources/sql/postgres/taskana_schema_update_4.11.0_to_5.0.0_postgres.sql

@@ -4,6 +4,8 @@ SET search_path = %schemaName%;
 
 INSERT INTO TASKANA_SCHEMA_VERSION (VERSION, CREATED) VALUES ('5.0.0', CURRENT_TIMESTAMP);
 
+ALTER TABLE OBJECT_REFERENCE ADD COLUMN TASK_ID VARCHAR(40) NOT NULL DEFAULT 'EMPTY';
+
 DROP INDEX IF EXISTS IDX_CLASSIFICATION_1;
 CREATE INDEX IDX_CLASSIFICATION_ID ON CLASSIFICATION
    (ID ASC, CUSTOM_8, CUSTOM_7, CUSTOM_6, CUSTOM_5, CUSTOM_4,

history/taskana-simplehistory-provider/src/test/java/acceptance/AbstractAccTest.java

@@ -30,6 +30,7 @@ import pro.taskana.simplehistory.impl.workbasket.WorkbasketHistoryEventMapper;
 import pro.taskana.spi.history.api.events.task.TaskHistoryEvent;
 import pro.taskana.spi.history.api.events.workbasket.WorkbasketHistoryEvent;
 import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 
 /** Set up database for tests. */
 public abstract class AbstractAccTest {
@@ -184,7 +185,7 @@ public abstract class AbstractAccTest {
 
   protected ObjectReference createObjectRef(
       String company, String system, String systemInstance, String type, String value) {
-    ObjectReference objectRef = new ObjectReference();
+    ObjectReferenceImpl objectRef = new ObjectReferenceImpl();
     objectRef.setCompany(company);
     objectRef.setSystem(system);
     objectRef.setSystemInstance(systemInstance);

lib/taskana-cdi-example/src/main/java/pro/taskana/example/ExampleBootstrap.java

@@ -12,10 +12,11 @@ import pro.taskana.common.api.exceptions.NotAuthorizedException;
 import pro.taskana.task.api.exceptions.AttachmentPersistenceException;
 import pro.taskana.task.api.exceptions.InvalidOwnerException;
 import pro.taskana.task.api.exceptions.InvalidStateException;
+import pro.taskana.task.api.exceptions.ObjectReferencePersistenceException;
 import pro.taskana.task.api.exceptions.TaskAlreadyExistException;
 import pro.taskana.task.api.exceptions.TaskNotFoundException;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.workbasket.api.exceptions.WorkbasketNotFoundException;
 
 /** Example Bootstrap Application. */
@@ -28,9 +29,10 @@ public class ExampleBootstrap {
   public void init(@Observes @Initialized(ApplicationScoped.class) Object init)
       throws TaskNotFoundException, NotAuthorizedException, WorkbasketNotFoundException,
           ClassificationNotFoundException, InvalidStateException, InvalidOwnerException,
-          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException {
+          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException,
+          ObjectReferencePersistenceException {
     System.out.println("---------------------------> Start App");
-    ObjectReference objRef = new ObjectReference();
+    ObjectReferenceImpl objRef = new ObjectReferenceImpl();
     objRef.setCompany("aCompany");
     objRef.setSystem("aSystem");
     objRef.setSystemInstance("anInstance");

lib/taskana-cdi/src/test/java/pro/taskana/TaskanaCdiTestRestController.java

@@ -13,8 +13,8 @@ import org.slf4j.LoggerFactory;
 
 import pro.taskana.classification.api.ClassificationService;
 import pro.taskana.classification.api.models.Classification;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.workbasket.api.WorkbasketType;
 import pro.taskana.workbasket.api.models.Workbasket;
 
@@ -39,7 +39,7 @@ public class TaskanaCdiTestRestController {
 
     Task task = taskanaEjb.getTaskService().newTask(workbasket.getKey());
     task.setClassificationKey(classification.getKey());
-    ObjectReference objRef = new ObjectReference();
+    ObjectReferenceImpl objRef = new ObjectReferenceImpl();
     objRef.setCompany("aCompany");
     objRef.setSystem("aSystem");
     objRef.setSystemInstance("anInstance");

lib/taskana-cdi/src/test/java/pro/taskana/TaskanaEjb.java

@@ -9,9 +9,10 @@ import pro.taskana.common.api.exceptions.InvalidArgumentException;
 import pro.taskana.common.api.exceptions.NotAuthorizedException;
 import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.exceptions.AttachmentPersistenceException;
+import pro.taskana.task.api.exceptions.ObjectReferencePersistenceException;
 import pro.taskana.task.api.exceptions.TaskAlreadyExistException;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.workbasket.api.WorkbasketService;
 import pro.taskana.workbasket.api.exceptions.WorkbasketNotFoundException;
 
@@ -38,9 +39,10 @@ public class TaskanaEjb {
 
   public void triggerRollback()
       throws NotAuthorizedException, WorkbasketNotFoundException, ClassificationNotFoundException,
-          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException {
+          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException,
+          ObjectReferencePersistenceException {
     final Task task = taskService.newTask(null);
-    ObjectReference objRef = new ObjectReference();
+    ObjectReferenceImpl objRef = new ObjectReferenceImpl();
     objRef.setCompany("aCompany");
     objRef.setSystem("aSystem");
     objRef.setSystemInstance("anInstance");

lib/taskana-core/src/main/java/pro/taskana/common/internal/TaskanaEngineImpl.java

@@ -144,6 +144,7 @@ public class TaskanaEngineImpl implements TaskanaEngine {
         sessionManager.getMapper(TaskMapper.class),
         sessionManager.getMapper(TaskCommentMapper.class),
         sessionManager.getMapper(AttachmentMapper.class),
+        sessionManager.getMapper(ObjectReferenceMapper.class),
         sessionManager.getMapper(UserMapper.class));
   }
 

lib/taskana-core/src/main/java/pro/taskana/task/api/TaskQuery.java

@@ -1458,6 +1458,50 @@ public interface TaskQuery extends BaseQuery<TaskSummary, TaskQueryColumnName> {
   TaskQuery orderByAttachmentReceived(SortDirection sortDirection);
 
   // endregion
+  // region secondaryObjectReference
+
+  /**
+   * Add the {@link ObjectReference} to exact match to your query. Each individual value has to
+   * match. Fields with the value 'null' will be ignored. The id of each ObjectReference will be
+   * ignored
+   *
+   * <p>If you specify multiple arguments they are combined with the OR keyword.
+   *
+   * @param objectReferences the combined values which are searched together.
+   * @return the query
+   */
+  TaskQuery secondaryObjectReferenceIn(ObjectReference... objectReferences);
+
+  // endregion
+  // region secondaryObjectReferenceCompany
+  TaskQuery sorCompanyIn(String... companyIn);
+
+  TaskQuery sorCompanyLike(String... companyLike);
+
+  // endregion
+  // region secondaryObjectReferenceSystem
+  TaskQuery sorSystemIn(String... systemIn);
+
+  TaskQuery sorSystemLike(String... systemLike);
+
+  // endregion
+  // region secondaryObjectReferenceSystemInstance
+  TaskQuery sorSystemInstanceIn(String... systemInstanceIn);
+
+  TaskQuery sorSystemInstanceLike(String... systemInstanceLike);
+
+  // endregion
+  // region secondaryObjectReferenceType
+  TaskQuery sorTypeIn(String... typeIn);
+
+  TaskQuery sorTypeLike(String... typeLike);
+
+  // endregion
+  // region secondaryObjectReferenceValue
+  TaskQuery sorValueIn(String... valueIn);
+
+  TaskQuery sorValueLike(String... valueLike);
+
   // region customAttributes
 
   /**

lib/taskana-core/src/main/java/pro/taskana/task/api/TaskQueryColumnName.java

@@ -57,7 +57,12 @@ public enum TaskQueryColumnName implements QueryColumnName {
   A_CLASSIFICATION_ID("a.classification_id"),
   A_CLASSIFICATION_KEY("a.classification_key"),
   A_CHANNEL("a.channel"),
-  A_REF_VALUE("a.ref_value");
+  A_REF_VALUE("a.ref_value"),
+  O_COMPANY("o.company"),
+  O_SYSTEM("o.system"),
+  O_SYSTEM_INSTANCE("o.system_instance"),
+  O_TYPE("o.type"),
+  O_VALUE("o.value");
 
   private final String name;
 
@@ -69,6 +74,10 @@ public enum TaskQueryColumnName implements QueryColumnName {
     return this.name().startsWith("A_");
   }
 
+  public boolean isObjectReferenceColumn() {
+    return this.name().startsWith("O_");
+  }
+
   @Override
   public String toString() {
     return name;

lib/taskana-core/src/main/java/pro/taskana/task/api/TaskService.java

@@ -13,6 +13,7 @@ import pro.taskana.common.api.exceptions.TaskanaException;
 import pro.taskana.task.api.exceptions.AttachmentPersistenceException;
 import pro.taskana.task.api.exceptions.InvalidOwnerException;
 import pro.taskana.task.api.exceptions.InvalidStateException;
+import pro.taskana.task.api.exceptions.ObjectReferencePersistenceException;
 import pro.taskana.task.api.exceptions.TaskAlreadyExistException;
 import pro.taskana.task.api.exceptions.TaskCommentNotFoundException;
 import pro.taskana.task.api.exceptions.TaskNotFoundException;
@@ -145,10 +146,13 @@ public interface TaskService {
    * @throws InvalidArgumentException thrown if the primary ObjectReference is invalid
    * @throws AttachmentPersistenceException if an Attachment with ID will be added multiple times
    *     without using the task-methods
+   * @throws ObjectReferencePersistenceException if an ObjectReference with ID will be added
+   *     multiple times without using the task-methods
    */
   Task createTask(Task taskToCreate)
       throws NotAuthorizedException, WorkbasketNotFoundException, ClassificationNotFoundException,
-          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException;
+          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException,
+          ObjectReferencePersistenceException;
 
   /**
    * Gets the details of a task by Id without checking permissions.
@@ -312,6 +316,16 @@ public interface TaskService {
    */
   Attachment newAttachment();
 
+  /**
+   * Returns a not inserted instance of {@link ObjectReference}.
+   *
+   * @return an empty new ObjectReference
+   */
+  ObjectReference newObjectReference();
+
+  ObjectReference newObjectReference(
+      String company, String system, String systemInstance, String type, String value);
+
   /**
    * Update a task.
    *
@@ -326,13 +340,15 @@ public interface TaskService {
    * @throws NotAuthorizedException if the current user is not authorized to update the task
    * @throws AttachmentPersistenceException if an Attachment with ID will be added multiple times
    *     without using the task-methods
+   * @throws ObjectReferencePersistenceException if an ObjectReference with ID will be added
+   *     multiple times without using the task-methods
    * @throws InvalidStateException if an attempt is made to change the owner of the task and the
    *     task is not in state READY .
    */
   Task updateTask(Task task)
       throws InvalidArgumentException, TaskNotFoundException, ConcurrencyException,
           ClassificationNotFoundException, NotAuthorizedException, AttachmentPersistenceException,
-          InvalidStateException;
+          ObjectReferencePersistenceException, InvalidStateException;
 
   /**
    * Transfers a list of {@linkplain Task Tasks} to another {@linkplain

lib/taskana-core/src/main/java/pro/taskana/task/api/exceptions/ObjectReferencePersistenceException.java

@@ -0,0 +1,42 @@
+package pro.taskana.task.api.exceptions;
+
+import pro.taskana.common.api.exceptions.ErrorCode;
+import pro.taskana.common.api.exceptions.TaskanaException;
+import pro.taskana.common.internal.util.MapCreator;
+import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.api.models.Task;
+
+/**
+ * This exception is thrown when an {@linkplain ObjectReference} should be inserted to the DB, but
+ * it does already exist. <br>
+ * This may happen when a not inserted {@linkplain ObjectReference} with the same {@linkplain
+ * ObjectReference#getId() id} will be added twice on a {@linkplain Task}. This can't happen if the
+ * correct {@linkplain Task}-Methods will be used instead of the List ones.
+ */
+public class ObjectReferencePersistenceException extends TaskanaException {
+  public static final String ERROR_KEY = "OBJECT_REFERENCE_ALREADY_EXISTS";
+  private final String objectReferenceId;
+  private final String taskId;
+
+  public ObjectReferencePersistenceException(
+      String objectReferenceId, String taskId, Throwable cause) {
+    super(
+        String.format(
+            "Cannot insert ObjectReference with id '%s' for Task with id '%s' "
+                + "because it already exists.",
+            objectReferenceId, taskId),
+        ErrorCode.of(
+            ERROR_KEY, MapCreator.of("objectReferenceId", objectReferenceId, "taskId", taskId)),
+        cause);
+    this.objectReferenceId = objectReferenceId;
+    this.taskId = taskId;
+  }
+
+  public String getObjectReferenceId() {
+    return objectReferenceId;
+  }
+
+  public String getTaskId() {
+    return taskId;
+  }
+}

lib/taskana-core/src/main/java/pro/taskana/task/api/models/ObjectReference.java

@@ -1,135 +1,96 @@
 package pro.taskana.task.api.models;
 
-import java.util.Objects;
+/** ObjectReference-Interface to specify ObjectReference Attributes. */
+public interface ObjectReference {
 
-import pro.taskana.common.api.exceptions.InvalidArgumentException;
+  /**
+   * Gets the id of the ObjectReference.
+   *
+   * @return the id of the ObjectReference.
+   */
+  String getId();
 
-/** ObjectReference entity. */
+  /**
-public class ObjectReference {
+   * Gets the id of the associated task.
-  private String id;
+   *
-  private String company;
+   * @return the taskId
-  private String system;
+   */
-  private String systemInstance;
+  String getTaskId();
-  private String type;
-  private String value;
 
-  public ObjectReference() {}
+  /**
+   * Gets the company of the ObjectReference.
+   *
+   * @return the company
+   */
+  String getCompany();
 
-  private ObjectReference(ObjectReference copyFrom) {
+  /**
-    company = copyFrom.company;
+   * Sets the company of the ObjectReference.
-    system = copyFrom.system;
+   *
-    systemInstance = copyFrom.systemInstance;
+   * @param company the company of the object reference
-    type = copyFrom.type;
+   */
-    value = copyFrom.value;
+  void setCompany(String company);
-  }
 
-  public static void validate(ObjectReference objectReference, String objRefType, String objName)
+  /**
-      throws InvalidArgumentException {
+   * Gets the system of the ObjectReference.
-    // check that all values in the ObjectReference are set correctly
+   *
-    if (objectReference == null) {
+   * @return the system
-      throw new InvalidArgumentException(
+   */
-          String.format("%s of %s must not be null.", objRefType, objName));
+  String getSystem();
-    } else if (objectReference.getCompany() == null || objectReference.getCompany().isEmpty()) {
-      throw new InvalidArgumentException(
-          String.format("Company of %s of %s must not be empty", objRefType, objName));
-    } else if (objectReference.getType() == null || objectReference.getType().length() == 0) {
-      throw new InvalidArgumentException(
-          String.format("Type of %s of %s must not be empty", objRefType, objName));
-    } else if (objectReference.getValue() == null || objectReference.getValue().length() == 0) {
-      throw new InvalidArgumentException(
-          String.format("Value of %s of %s must not be empty", objRefType, objName));
-    }
-  }
 
-  public String getId() {
+  /**
-    return id;
+   * Sets the system of the ObjectReference.
-  }
+   *
+   * @param system the system of the ObjectReference
+   */
+  void setSystem(String system);
 
-  public void setId(String id) {
+  /**
-    this.id = id;
+   * Gets the systemInstance of the ObjectReference.
-  }
+   *
+   * @return the systemInstance
+   */
+  String getSystemInstance();
 
-  public String getCompany() {
+  /**
-    return company;
+   * Sets the system instance of the ObjectReference.
-  }
+   *
+   * @param systemInstance the system instance of the ObjectReference
+   */
+  void setSystemInstance(String systemInstance);
 
-  public void setCompany(String company) {
+  /**
-    this.company = company;
+   * Gets the type of the ObjectReference.
-  }
+   *
+   * @return the type
+   */
+  String getType();
 
-  public String getSystem() {
+  /**
-    return system;
+   * Sets the type of the ObjectReference.
-  }
+   *
+   * @param type the type of the ObjectReference
+   */
+  void setType(String type);
 
-  public void setSystem(String system) {
+  /**
-    this.system = system;
+   * Gets the value of the ObjectReference.
-  }
+   *
+   * @return the value
+   */
+  String getValue();
 
-  public String getSystemInstance() {
+  /**
-    return systemInstance;
+   * Sets the value of the ObjectReference.
-  }
+   *
+   * @param value the value of the ObjectReference
+   */
+  void setValue(String value);
 
-  public void setSystemInstance(String systemInstance) {
+  /**
-    this.systemInstance = systemInstance;
+   * Duplicates this ObjectReference without the id and taskId.
-  }
+   *
-
+   * @return a copy of this ObjectReference
-  public String getType() {
+   */
-    return type;
+  ObjectReference copy();
-  }
-
-  public void setType(String type) {
-    this.type = type;
-  }
-
-  public String getValue() {
-    return value;
-  }
-
-  public void setValue(String value) {
-    this.value = value;
-  }
-
-  public ObjectReference copy() {
-    return new ObjectReference(this);
-  }
-
-  @Override
-  public int hashCode() {
-    return Objects.hash(id, company, system, systemInstance, type, value);
-  }
-
-  @Override
-  public boolean equals(Object obj) {
-    if (this == obj) {
-      return true;
-    }
-    if (!(obj instanceof ObjectReference)) {
-      return false;
-    }
-    ObjectReference other = (ObjectReference) obj;
-    return Objects.equals(id, other.id)
-        && Objects.equals(company, other.company)
-        && Objects.equals(system, other.system)
-        && Objects.equals(systemInstance, other.systemInstance)
-        && Objects.equals(type, other.type)
-        && Objects.equals(value, other.value);
-  }
-
-  @Override
-  public String toString() {
-    return "ObjectReference ["
-        + "id="
-        + this.id
-        + ", company="
-        + this.company
-        + ", system="
-        + this.system
-        + ", systemInstance="
-        + this.systemInstance
-        + ", type="
-        + this.type
-        + ", value="
-        + this.value
-        + "]";
-  }
 }

lib/taskana-core/src/main/java/pro/taskana/task/api/models/Task.java

@@ -19,10 +19,10 @@ public interface Task extends TaskSummary {
   String CALLBACK_STATE = "callbackState";
 
   /**
-   * Sets the external Id. It can be used to correlate the task to a task in an external system. The
+   * Sets the external Id. It can be used to correlate the Task to a Task in an external system. The
-   * external Id is enforced to be unique. An attempt to create a task with an existing external Id
+   * external Id is enforced to be unique. An attempt to create a Task with an existing external Id
-   * will be rejected. So, this Id can be used to enforce idempotency of task creation. The
+   * will be rejected. So, this Id can be used to enforce idempotency of Task creation. The
-   * externalId can only be set before the task is inserted. Taskana rejects attempts to modify
+   * externalId can only be set before the Task is inserted. Taskana rejects attempts to modify
    * externalId.
    *
    * @param externalId the external Id
@@ -30,7 +30,7 @@ public interface Task extends TaskSummary {
   void setExternalId(String externalId);
 
   /**
-   * Sets the time when the work on this task should be started.
+   * Sets the time when the work on this Task should be started.
    *
    * @param planned as exact {@link Instant}
    */
@@ -44,36 +44,36 @@ public interface Task extends TaskSummary {
   void setReceived(Instant received);
 
   /**
-   * Sets the time when the work on this task should be finished.
+   * Sets the time when the work on this Task should be finished.
    *
    * @param due as exact {@link Instant}
    */
   void setDue(Instant due);
 
   /**
-   * Sets the name of the current task.
+   * Sets the name of the current Task.
    *
-   * @param name the name of the task
+   * @param name the name of the Task
    */
   void setName(String name);
 
   /**
-   * Sets the description of the task.
+   * Sets the description of the Task.
    *
-   * @param description the description of the task
+   * @param description the description of the Task
    */
   void setDescription(String description);
 
   /**
-   * Sets the Classification key that - together with the Domain from this task's work basket -
+   * Sets the Classification key that - together with the Domain from this Task's work basket -
-   * selects the appropriate {@link Classification} for this task.
+   * selects the appropriate {@link Classification} for this Task.
    *
-   * @param classificationKey the classification key for the task
+   * @param classificationKey the classification key for the Task
    */
   void setClassificationKey(String classificationKey);
 
   /**
-   * Returns the key of the Workbasket where the task is stored in.
+   * Returns the key of the Workbasket where the Task is stored in.
    *
    * @return workbasketKey
    */
@@ -119,47 +119,59 @@ public interface Task extends TaskSummary {
    * Add an attachment.<br>
    * NULL will be ignored and an attachment with the same ID will be replaced by the newer one.<br>
    *
-   * @param attachment the {@link Attachment attachment} to be added to the task
+   * @param attachment the {@link Attachment attachment} to be added to the Task
    */
   void addAttachment(Attachment attachment);
 
   /**
-   * Return the attachments for this task. <br>
+   * Return the attachments for this Task. <br>
    * Do not use List.add()/addAll() for adding Elements, because it can cause redundant data. Use
    * addAttachment(). Clear() and remove() can be used, because it's a controllable change.
    *
-   * @return the {@link List list} of {@link Attachment attachments} for this task
+   * @return the {@link List list} of {@link Attachment attachments} for this Task
    */
   List<Attachment> getAttachments();
 
   /**
    * Sets the external business process id.
    *
-   * @param businessProcessId Sets the business process id the task belongs to.
+   * @param businessProcessId Sets the business process id the Task belongs to.
    */
   void setBusinessProcessId(String businessProcessId);
 
   /**
    * Sets the parent business process id to group associated processes.
    *
-   * @param parentBusinessProcessId Sets the parent business process id the task belongs to
+   * @param parentBusinessProcessId Sets the parent business process id the Task belongs to
    */
   void setParentBusinessProcessId(String parentBusinessProcessId);
 
   /**
-   * Sets the ownerId of this task.
+   * Sets the ownerId of this Task.
    *
-   * @param taskOwnerId the user id of the task's owner
+   * @param taskOwnerId the user id of the Task's owner
    */
   void setOwner(String taskOwnerId);
 
   /**
-   * Sets the {@link ObjectReference primaryObjectReference} of the task.
+   * Sets the {@link ObjectReference primaryObjectReference} of the Task.
    *
-   * @param primaryObjRef to task main-subject
+   * @param primaryObjRef to Task main-subject
    */
   void setPrimaryObjRef(ObjectReference primaryObjRef);
 
+  /**
+   * Initializes and sets the {@link ObjectReference primaryObjectReference} of the Task.
+   *
+   * @param company of the {@link ObjectReference primaryObjectReference} to be set
+   * @param system of the {@link ObjectReference primaryObjectReference} to be set
+   * @param systemInstance of the {@link ObjectReference primaryObjectReference} to be set
+   * @param type of the {@link ObjectReference primaryObjectReference} to be set
+   * @param value of the {@link ObjectReference primaryObjectReference} to be set
+   */
+  void setPrimaryObjRef(
+      String company, String system, String systemInstance, String type, String value);
+
   /**
    * Sets/Changing the custom note for this Task.
    *
@@ -170,12 +182,12 @@ public interface Task extends TaskSummary {
   /**
    * Return a summary of the current Task.
    *
-   * @return the TaskSummary object for the current task
+   * @return the TaskSummary object for the current Task
    */
   TaskSummary asSummary();
 
   /**
-   * Removes an attachment of the current task locally, when the ID is represented and does return
+   * Removes an attachment of the current Task locally, when the ID is represented and does return
    * the removed attachment or null if there was no match.<br>
    * The changed Task need to be updated calling the {@link TaskService#updateTask(Task)}.
    *
@@ -194,7 +206,7 @@ public interface Task extends TaskSummary {
 
   /**
    * Duplicates this Task without the internal and external id. All referenced {@link Attachment}s
-   * are copied as well.
+   * and {@link ObjectReference}s are copied as well.
    *
    * @return a copy of this Task
    */

lib/taskana-core/src/main/java/pro/taskana/task/api/models/TaskSummary.java

@@ -5,6 +5,7 @@ import java.util.List;
 
 import pro.taskana.classification.api.models.ClassificationSummary;
 import pro.taskana.task.api.TaskCustomField;
+import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.TaskState;
 import pro.taskana.workbasket.api.models.WorkbasketSummary;
 
@@ -15,21 +16,21 @@ import pro.taskana.workbasket.api.models.WorkbasketSummary;
 public interface TaskSummary {
 
   /**
-   * Gets the id of the task.
+   * Gets the id of the Task.
    *
    * @return taskId
    */
   String getId();
 
   /**
-   * Gets the external id of the task.
+   * Gets the external id of the Task.
    *
    * @return the external Id
    */
   String getExternalId();
 
   /**
-   * Gets the name of the task-creator.
+   * Gets the name of the creator of the Task.
    *
    * @return creator
    */
@@ -38,133 +39,176 @@ public interface TaskSummary {
   /**
    * Gets the time when the task was created.
    *
-   * @return the created Instant
+   * @return the created {@link Instant}
    */
   Instant getCreated();
 
   /**
-   * Gets the time when the task was claimed.
+   * Gets the time when the Task was claimed.
    *
-   * @return the claimed Instant
+   * @return the claimed {@link Instant}
    */
   Instant getClaimed();
 
   /**
-   * Gets the time when the task was completed.
+   * Gets the time when the Task was completed.
    *
-   * @return the completed Instant
+   * @return the completed {@link Instant}
    */
   Instant getCompleted();
 
   /**
-   * Gets the time when the task was last modified.
+   * Gets the time when the Task was last modified.
    *
-   * @return the last modified Instant
+   * @return the last modified {@link Instant}
    */
   Instant getModified();
 
   /**
-   * Gets the time when the task is planned to be executed.
+   * Gets the time when the Task is planned to be executed.
    *
-   * @return the planned Instant
+   * @return the planned {@link Instant}
    */
   Instant getPlanned();
 
   /**
-   * Gets the time when when the surrounding process was started.
+   * Gets the time when the surrounding process was started.
    *
-   * @return the received Instant
+   * @return the received {@link Instant}
    */
   Instant getReceived();
 
   /**
-   * Gets the time when the task is due.
+   * Gets the time when the Task is due.
    *
-   * @return the due Instant
+   * @return the due {@link Instant}
    */
   Instant getDue();
 
   /**
-   * Gets the name of the task.
+   * Gets the name of the Task.
    *
-   * @return the task's name
+   * @return the Task's name
    */
   String getName();
 
   /**
-   * Gets the note attached to the task.
+   * Gets the note attached to the Task.
    *
-   * @return the task's note
+   * @return the Task's note
    */
   String getNote();
 
   /**
-   * Gets the description of the task.
+   * Gets the description of the Task.
    *
-   * @return the task's description
+   * @return the Task's description
    */
   String getDescription();
 
   /**
-   * Gets the priority of the task.
+   * Gets the priority of the Task.
    *
-   * @return the task's priority
+   * @return the Task's priority
    */
   int getPriority();
 
   /**
-   * Gets the state of the task.
+   * Gets the state of the Task.
    *
-   * @return the task's state
+   * @return the Task's state
    */
   TaskState getState();
 
   /**
-   * Gets the classification summary of the task.
+   * Gets the {@link ClassificationSummary} of the Task.
    *
-   * @return the task's classificationSummary
+   * @return the Task's {@link ClassificationSummary}
    */
   ClassificationSummary getClassificationSummary();
 
   /**
-   * Gets the workbasket summary of the task.
+   * Gets the {@link WorkbasketSummary} of the Task.
    *
-   * @return the task's workbasketSummary
+   * @return the Task's {@link WorkbasketSummary}
    */
   WorkbasketSummary getWorkbasketSummary();
 
   /**
-   * Gets the attachment summaries of the task.
+   * Gets the {@link AttachmentSummary attachmentSummaries} of the Task.
    *
-   * @return the task's attachment summaries
+   * @return the Task's {@link AttachmentSummary attachmentSummaries}
    */
   List<AttachmentSummary> getAttachmentSummaries();
 
   /**
-   * Gets the domain of the task.
+   * Gets the secondary {@link ObjectReference}s of the Task.
    *
-   * @return the task's domain
+   * @return the Task's secondary {@link ObjectReference}s
+   */
+  List<ObjectReference> getSecondaryObjectReferences();
+
+  /**
+   * Add an {@link ObjectReference} to the list of secondary {@link ObjectReference}s.<br>
+   * NULL will be ignored and an ObjectReference with the same ID will be replaced by the newer one.
+   * <br>
+   *
+   * @param objectReference the secondary {@link ObjectReference objectReference} to be added to the
+   *     Task
+   */
+  void addSecondaryObjectReference(ObjectReference objectReference);
+
+  /**
+   * Add an {@link ObjectReference} to the list of secondary {@link ObjectReference}s.<br>
+   * NULL will be ignored and an ObjectReference with the same ID will be replaced by the newer one.
+   * <br>
+   *
+   * @param company of the {@link ObjectReference objectReference} to be added to the Task
+   * @param system of the {@link ObjectReference objectReference} to be added to the Task
+   * @param systemInstance of the {@link ObjectReference objectReference} to be added to the Task
+   * @param type of the {@link ObjectReference objectReference} to be added to the Task
+   * @param value of the {@link ObjectReference objectReference} to be added to the Task
+   */
+  void addSecondaryObjectReference(
+      String company, String system, String systemInstance, String type, String value);
+
+  /**
+   * Removes a secondary {@link ObjectReference} of the current Task locally, when the ID is
+   * represented and does return the removed {@link ObjectReference} or null if there was no match.
+   * <br>
+   * The changed Task need to be updated calling the {@link TaskService#updateTask(Task)}.
+   *
+   * @param objectReferenceID ID of the {@link ObjectReference} which should be removed.
+   * @return the {@link ObjectReference} which will be removed after updating OR null if there was
+   *     no matching {@link ObjectReference}
+   */
+  ObjectReference removeSecondaryObjectReference(String objectReferenceID);
+
+  /**
+   * Gets the domain of the Task.
+   *
+   * @return the Task's domain
    */
   String getDomain();
 
   /**
-   * Gets the businessProcessId of the task.
+   * Gets the businessProcessId of the Task.
    *
-   * @return the task's businessProcessId
+   * @return the Task's businessProcessId
    */
   String getBusinessProcessId();
 
   /**
-   * Gets the parentBusinessProcessId of the task.
+   * Gets the parentBusinessProcessId of the Task.
    *
-   * @return the task's parentBusinessProcessId
+   * @return the Task's parentBusinessProcessId
    */
   String getParentBusinessProcessId();
 
   /**
-   * Gets the owner of the task.
+   * Gets the owner of the Task.
    *
-   * @return the task's owner
+   * @return the Task's owner
    */
   String getOwner();
 
@@ -176,28 +220,28 @@ public interface TaskSummary {
   String getOwnerLongName();
 
   /**
-   * Gets the primary ObjectReference of the task.
+   * Gets the primary {@link ObjectReference} of the Task.
    *
-   * @return the task's primary ObjectReference
+   * @return the Task's primary {@link ObjectReference}
    */
   ObjectReference getPrimaryObjRef();
 
   /**
-   * Gets the isRead flag of the task.
+   * Gets the isRead flag of the Task.
    *
-   * @return the task's isRead flag
+   * @return the Task's isRead flag
    */
   boolean isRead();
 
   /**
-   * Gets the isTransferred flag of the task.
+   * Gets the isTransferred flag of the Task.
    *
-   * @return the task's isTransferred flag.
+   * @return the Task's isTransferred flag.
    */
   boolean isTransferred();
 
   /**
-   * Gets the custom attribute of the task.
+   * Gets the custom attribute of the Task.
    *
    * @param customField identifies which custom attribute is requested.
    * @return the value for the given customField

lib/taskana-core/src/main/java/pro/taskana/task/internal/AttachmentHandler.java

@@ -19,9 +19,9 @@ import pro.taskana.common.internal.util.IdGenerator;
 import pro.taskana.task.api.exceptions.AttachmentPersistenceException;
 import pro.taskana.task.api.models.Attachment;
 import pro.taskana.task.api.models.AttachmentSummary;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
 import pro.taskana.task.internal.models.AttachmentImpl;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.internal.models.TaskImpl;
 
 public class AttachmentHandler {
@@ -183,7 +183,7 @@ public class AttachmentHandler {
       throw new InvalidArgumentException("ClassificationKey of Attachment must not be empty.");
     }
 
-    ObjectReference.validate(attachment.getObjectReference(), "ObjectReference", "Attachment");
+    ObjectReferenceImpl.validate(attachment.getObjectReference(), "ObjectReference", "Attachment");
 
     classification =
         classificationService

lib/taskana-core/src/main/java/pro/taskana/task/internal/AttachmentMapper.java

@@ -23,8 +23,8 @@ public interface AttachmentMapper {
 
   @Insert(
       "INSERT INTO ATTACHMENT (ID, TASK_ID, CREATED, MODIFIED, CLASSIFICATION_KEY, CLASSIFICATION_ID, REF_COMPANY, REF_SYSTEM, REF_INSTANCE, REF_TYPE, REF_VALUE, CHANNEL, RECEIVED, CUSTOM_ATTRIBUTES) "
-          + "VALUES (#{att.id}, #{att.taskId}, #{att.created}, #{att.modified}, #{att.classificationSummary.key}, #{att.classificationSummary.id}, #{att.objectReference.company}, #{att.objectReference.system}, #{att.objectReference.systemInstance}, "
+          + "VALUES (#{att.id}, #{att.taskId}, #{att.created}, #{att.modified}, #{att.classificationSummary.key}, #{att.classificationSummary.id}, #{att.objectReferenceImpl.company}, #{att.objectReferenceImpl.system}, #{att.objectReferenceImpl.systemInstance}, "
-          + " #{att.objectReference.type}, #{att.objectReference.value}, #{att.channel}, #{att.received}, #{att.customAttributes,jdbcType=CLOB,javaType=java.util.Map,typeHandler=pro.taskana.common.internal.persistence.MapTypeHandler} )")
+          + " #{att.objectReferenceImpl.type}, #{att.objectReferenceImpl.value}, #{att.channel}, #{att.received}, #{att.customAttributes,jdbcType=CLOB,javaType=java.util.Map,typeHandler=pro.taskana.common.internal.persistence.MapTypeHandler} )")
   void insert(@Param("att") AttachmentImpl att);
 
   @Select(
@@ -39,11 +39,11 @@ public interface AttachmentMapper {
   @Result(property = "modified", column = "MODIFIED")
   @Result(property = "classificationSummaryImpl.key", column = "CLASSIFICATION_KEY")
   @Result(property = "classificationSummaryImpl.id", column = "CLASSIFICATION_ID")
-  @Result(property = "objectReference.company", column = "REF_COMPANY")
+  @Result(property = "objectReferenceImpl.company", column = "REF_COMPANY")
-  @Result(property = "objectReference.system", column = "REF_SYSTEM")
+  @Result(property = "objectReferenceImpl.system", column = "REF_SYSTEM")
-  @Result(property = "objectReference.systemInstance", column = "REF_INSTANCE")
+  @Result(property = "objectReferenceImpl.systemInstance", column = "REF_INSTANCE")
-  @Result(property = "objectReference.type", column = "REF_TYPE")
+  @Result(property = "objectReferenceImpl.type", column = "REF_TYPE")
-  @Result(property = "objectReference.value", column = "REF_VALUE")
+  @Result(property = "objectReferenceImpl.value", column = "REF_VALUE")
   @Result(property = "channel", column = "CHANNEL")
   @Result(property = "received", column = "RECEIVED")
   @Result(
@@ -74,11 +74,11 @@ public interface AttachmentMapper {
   @Result(property = "modified", column = "MODIFIED")
   @Result(property = "classificationSummaryImpl.key", column = "CLASSIFICATION_KEY")
   @Result(property = "classificationSummaryImpl.id", column = "CLASSIFICATION_ID")
-  @Result(property = "objectReference.company", column = "REF_COMPANY")
+  @Result(property = "objectReferenceImpl.company", column = "REF_COMPANY")
-  @Result(property = "objectReference.system", column = "REF_SYSTEM")
+  @Result(property = "objectReferenceImpl.system", column = "REF_SYSTEM")
-  @Result(property = "objectReference.systemInstance", column = "REF_INSTANCE")
+  @Result(property = "objectReferenceImpl.systemInstance", column = "REF_INSTANCE")
-  @Result(property = "objectReference.type", column = "REF_TYPE")
+  @Result(property = "objectReferenceImpl.type", column = "REF_TYPE")
-  @Result(property = "objectReference.value", column = "REF_VALUE")
+  @Result(property = "objectReferenceImpl.value", column = "REF_VALUE")
   @Result(property = "channel", column = "CHANNEL")
   @Result(property = "received", column = "RECEIVED")
   List<AttachmentSummaryImpl> findAttachmentSummariesByTaskIds(
@@ -93,8 +93,8 @@ public interface AttachmentMapper {
 
   @Update(
       "UPDATE ATTACHMENT SET TASK_ID = #{taskId}, CREATED = #{created}, MODIFIED = #{modified},"
-          + " CLASSIFICATION_KEY = #{classificationSummary.key}, CLASSIFICATION_ID = #{classificationSummary.id}, REF_COMPANY = #{objectReference.company}, REF_SYSTEM = #{objectReference.system},"
+          + " CLASSIFICATION_KEY = #{classificationSummary.key}, CLASSIFICATION_ID = #{classificationSummary.id}, REF_COMPANY = #{objectReferenceImpl.company}, REF_SYSTEM = #{objectReferenceImpl.system},"
-          + " REF_INSTANCE = #{objectReference.systemInstance}, REF_TYPE = #{objectReference.type}, REF_VALUE = #{objectReference.value},"
+          + " REF_INSTANCE = #{objectReferenceImpl.systemInstance}, REF_TYPE = #{objectReferenceImpl.type}, REF_VALUE = #{objectReferenceImpl.value},"
           + " CHANNEL = #{channel}, RECEIVED = #{received}, CUSTOM_ATTRIBUTES = #{customAttributes,jdbcType=CLOB,javaType=java.util.Map,typeHandler=pro.taskana.common.internal.persistence.MapTypeHandler}"
           + " WHERE ID = #{id}")
   void update(AttachmentImpl attachment);

lib/taskana-core/src/main/java/pro/taskana/task/internal/ObjectReferenceHandler.java

@@ -0,0 +1,164 @@
+package pro.taskana.task.internal;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import org.apache.ibatis.exceptions.PersistenceException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import pro.taskana.common.api.exceptions.InvalidArgumentException;
+import pro.taskana.common.internal.util.IdGenerator;
+import pro.taskana.task.api.exceptions.ObjectReferencePersistenceException;
+import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
+import pro.taskana.task.internal.models.TaskImpl;
+
+/** Handles all operations on secondary {@link ObjectReference}s. */
+public class ObjectReferenceHandler {
+  private static final Logger LOGGER = LoggerFactory.getLogger(ObjectReferenceHandler.class);
+  private final ObjectReferenceMapper objectReferenceMapper;
+
+  ObjectReferenceHandler(ObjectReferenceMapper objectReferenceMapper) {
+    this.objectReferenceMapper = objectReferenceMapper;
+  }
+
+  void insertNewSecondaryObjectReferencesOnTaskCreation(TaskImpl task)
+      throws ObjectReferencePersistenceException, InvalidArgumentException {
+    List<ObjectReference> objectReferences = task.getSecondaryObjectReferences();
+
+    if (objectReferences != null) {
+      for (ObjectReference objectReference : objectReferences) {
+        ObjectReferenceImpl objectReferenceImpl = (ObjectReferenceImpl) objectReference;
+        initObjectReference(objectReferenceImpl, task);
+        ObjectReferenceImpl.validate(objectReferenceImpl, "ObjectReference", "Task");
+        try {
+          objectReferenceMapper.insert(objectReferenceImpl);
+          if (LOGGER.isDebugEnabled()) {
+            LOGGER.debug(
+                "TaskService.createTask() for TaskId={} INSERTED an object reference={}.",
+                task.getId(),
+                objectReference);
+          }
+        } catch (PersistenceException e) {
+          throw new ObjectReferencePersistenceException(objectReference.getId(), task.getId(), e);
+        }
+      }
+    }
+  }
+
+  void insertAndDeleteObjectReferencesOnTaskUpdate(TaskImpl newTaskImpl, TaskImpl oldTaskImpl)
+      throws ObjectReferencePersistenceException, InvalidArgumentException {
+    List<ObjectReference> newObjectReferences =
+        newTaskImpl.getSecondaryObjectReferences().stream()
+            .filter(Objects::nonNull)
+            .collect(Collectors.toList());
+    newTaskImpl.setSecondaryObjectReferences(newObjectReferences);
+
+    for (ObjectReference objectReference : newObjectReferences) {
+      ObjectReferenceImpl.validate(objectReference, "Object Reference", "Task");
+      initObjectReference((ObjectReferenceImpl) objectReference, newTaskImpl);
+    }
+
+    deleteRemovedObjectReferencesOnTaskUpdate(newTaskImpl, oldTaskImpl);
+    insertNewObjectReferencesOnTaskUpdate(newTaskImpl, oldTaskImpl);
+    updateModifiedObjectReferencesOnTaskUpdate(newTaskImpl, oldTaskImpl);
+  }
+
+  private void insertNewObjectReferencesOnTaskUpdate(TaskImpl newTaskImpl, TaskImpl oldTaskImpl)
+      throws ObjectReferencePersistenceException {
+    Set<String> oldObjectReferencesIds =
+        oldTaskImpl.getSecondaryObjectReferences().stream()
+            .map(ObjectReference::getId)
+            .collect(Collectors.toSet());
+
+    List<ObjectReference> newObjectReferences =
+        newTaskImpl.getSecondaryObjectReferences().stream()
+            .filter(o -> !oldObjectReferencesIds.contains(o.getId()))
+            .collect(Collectors.toList());
+
+    for (ObjectReference objectReference : newObjectReferences) {
+      insertNewObjectReferenceOnTaskUpdate(newTaskImpl, objectReference);
+    }
+  }
+
+  private void updateModifiedObjectReferencesOnTaskUpdate(
+      TaskImpl newTaskImpl, TaskImpl oldTaskImpl) {
+    List<ObjectReference> newObjectReferences = newTaskImpl.getSecondaryObjectReferences();
+    List<ObjectReference> oldObjectReferences = oldTaskImpl.getSecondaryObjectReferences();
+    if (newObjectReferences != null
+        && !newObjectReferences.isEmpty()
+        && oldObjectReferences != null
+        && !oldObjectReferences.isEmpty()) {
+      final Map<String, ObjectReference> oldObjectReferencesMap =
+          oldObjectReferences.stream()
+              .collect(Collectors.toMap(ObjectReference::getId, Function.identity()));
+      newObjectReferences.forEach(
+          o -> {
+            if (oldObjectReferencesMap.containsKey(o.getId())
+                && !o.equals(oldObjectReferencesMap.get(o.getId()))) {
+              objectReferenceMapper.update((ObjectReferenceImpl) o);
+            }
+          });
+    }
+  }
+
+  private void deleteRemovedObjectReferencesOnTaskUpdate(
+      TaskImpl newTaskImpl, TaskImpl oldTaskImpl) {
+
+    final List<ObjectReference> newObjectReferences = newTaskImpl.getSecondaryObjectReferences();
+    List<String> newObjectReferencesIds = new ArrayList<>();
+    if (newObjectReferences != null && !newObjectReferences.isEmpty()) {
+      newObjectReferencesIds =
+          newObjectReferences.stream().map(ObjectReference::getId).collect(Collectors.toList());
+    }
+    List<ObjectReference> oldObjectReferences = oldTaskImpl.getSecondaryObjectReferences();
+    if (oldObjectReferences != null && !oldObjectReferences.isEmpty()) {
+      final List<String> newObjRefIds = newObjectReferencesIds;
+      oldObjectReferences.forEach(
+          o -> {
+            if (!newObjRefIds.contains(o.getId())) {
+              objectReferenceMapper.delete(o.getId());
+              if (LOGGER.isDebugEnabled()) {
+                LOGGER.debug(
+                    "TaskService.updateTask() for TaskId={} DELETED an ObjectReference={}.",
+                    newTaskImpl.getId(),
+                    o);
+              }
+            }
+          });
+    }
+  }
+
+  private void insertNewObjectReferenceOnTaskUpdate(
+      TaskImpl newTaskImpl, ObjectReference objectReference)
+      throws ObjectReferencePersistenceException {
+    ObjectReferenceImpl objectReferenceImpl = (ObjectReferenceImpl) objectReference;
+    try {
+      objectReferenceMapper.insert(objectReferenceImpl);
+      if (LOGGER.isDebugEnabled()) {
+        LOGGER.debug(
+            "TaskService.updateTask() for TaskId={} INSERTED an ObjectReference={}.",
+            newTaskImpl.getId(),
+            objectReferenceImpl);
+      }
+    } catch (PersistenceException e) {
+      throw new ObjectReferencePersistenceException(
+          objectReferenceImpl.getId(), newTaskImpl.getId(), e);
+    }
+  }
+
+  private void initObjectReference(ObjectReferenceImpl objectReference, Task newTask) {
+    if (objectReference.getTaskId() == null) {
+      objectReference.setTaskId(newTask.getId());
+    }
+    if (objectReference.getId() == null) {
+      objectReference.setId(IdGenerator.generateWithPrefix(IdGenerator.ID_PREFIX_OBJECT_REFERENCE));
+    }
+  }
+}

lib/taskana-core/src/main/java/pro/taskana/task/internal/ObjectReferenceMapper.java

@@ -1,5 +1,6 @@
 package pro.taskana.task.internal;
 
+import java.util.Collection;
 import java.util.List;
 import org.apache.ibatis.annotations.Delete;
 import org.apache.ibatis.annotations.Insert;
@@ -9,7 +10,7 @@ import org.apache.ibatis.annotations.Select;
 import org.apache.ibatis.annotations.SelectProvider;
 import org.apache.ibatis.annotations.Update;
 
-import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 
 /** This class is the mybatis mapping of ObjectReference. */
 @SuppressWarnings({"checkstyle:LineLength", "checkstyle:Indentation"})
@@ -27,7 +28,47 @@ public interface ObjectReferenceMapper {
   @Result(property = "systemInstance", column = "SYSTEM_INSTANCE")
   @Result(property = "type", column = "TYPE")
   @Result(property = "value", column = "VALUE")
-  ObjectReference findById(@Param("id") String id);
+  ObjectReferenceImpl findById(@Param("id") String id);
+
+  @Select(
+      "<script>SELECT ID, TASK_ID, COMPANY, SYSTEM, SYSTEM_INSTANCE, TYPE, VALUE "
+          + "FROM OBJECT_REFERENCE "
+          + "WHERE TASK_ID = #{taskId}"
+          + "<if test=\"_databaseId == 'db2'\">with UR </if> "
+          + "</script>")
+  @Result(property = "id", column = "ID")
+  @Result(property = "taskId", column = "TASK_ID")
+  @Result(property = "company", column = "COMPANY")
+  @Result(property = "system", column = "SYSTEM")
+  @Result(property = "systemInstance", column = "SYSTEM_INSTANCE")
+  @Result(property = "type", column = "TYPE")
+  @Result(property = "value", column = "VALUE")
+  List<ObjectReferenceImpl> findObjectReferencesByTaskId(@Param("taskId") String taskId);
+
+  @Select(
+      "<script>SELECT ID, TASK_ID, COMPANY, SYSTEM, SYSTEM_INSTANCE, TYPE, VALUE "
+          + "FROM OBJECT_REFERENCE "
+          + "<where>"
+          + "<choose>"
+          + "<when  test='taskIds == null'>"
+          + " 1 = 2 "
+          + "</when>"
+          + "<otherwise>"
+          + "TASK_ID IN (<foreach collection='taskIds' item='item' separator=',' >#{item}</foreach>) "
+          + "</otherwise>"
+          + "</choose>"
+          + "</where>"
+          + "<if test=\"_databaseId == 'db2'\">with UR </if> "
+          + "</script>")
+  @Result(property = "id", column = "ID")
+  @Result(property = "taskId", column = "TASK_ID")
+  @Result(property = "company", column = "COMPANY")
+  @Result(property = "system", column = "SYSTEM")
+  @Result(property = "systemInstance", column = "SYSTEM_INSTANCE")
+  @Result(property = "type", column = "TYPE")
+  @Result(property = "value", column = "VALUE")
+  List<ObjectReferenceImpl> findObjectReferencesByTaskIds(
+      @Param("taskIds") Collection<String> taskIds);
 
   @Select(
       "<script>SELECT ID, COMPANY, SYSTEM, SYSTEM_INSTANCE, TYPE, VALUE "
@@ -45,7 +86,8 @@ public interface ObjectReferenceMapper {
   @Result(property = "systemInstance", column = "SYSTEM_INSTANCE")
   @Result(property = "type", column = "TYPE")
   @Result(property = "value", column = "VALUE")
-  ObjectReference findByObjectReference(@Param("objectReference") ObjectReference objectReference);
+  ObjectReferenceImpl findByObjectReference(
+      @Param("objectReference") ObjectReferenceImpl objectReference);
 
   @SelectProvider(type = ObjectReferenceQuerySqlProvider.class, method = "queryObjectReferences")
   @Result(property = "id", column = "ID")
@@ -54,7 +96,7 @@ public interface ObjectReferenceMapper {
   @Result(property = "systemInstance", column = "SYSTEM_INSTANCE")
   @Result(property = "type", column = "TYPE")
   @Result(property = "value", column = "VALUE")
-  List<ObjectReference> queryObjectReferences(ObjectReferenceQueryImpl objectReference);
+  List<ObjectReferenceImpl> queryObjectReferences(ObjectReferenceQueryImpl objectReference);
 
   @SelectProvider(
       type = ObjectReferenceQuerySqlProvider.class,
@@ -67,17 +109,21 @@ public interface ObjectReferenceMapper {
   List<String> queryObjectReferenceColumnValues(ObjectReferenceQueryImpl objectReference);
 
   @Insert(
-      "INSERT INTO OBJECT_REFERENCE (ID,  COMPANY, SYSTEM, SYSTEM_INSTANCE, TYPE, VALUE) "
+      "INSERT INTO OBJECT_REFERENCE (ID, TASK_ID, COMPANY, SYSTEM, SYSTEM_INSTANCE, TYPE, VALUE) "
-          + "VALUES (#{ref.id}, #{ref.company}, #{ref.system}, #{ref.systemInstance}, #{ref.type}, #{ref.value})")
+          + "VALUES (#{ref.id}, #{ref.taskId}, #{ref.company}, #{ref.system}, #{ref.systemInstance}, #{ref.type}, #{ref.value})")
-  void insert(@Param("ref") ObjectReference ref);
+  void insert(@Param("ref") ObjectReferenceImpl ref);
 
   @Update(
       value =
           "UPDATE OBJECT_REFERENCE "
               + "SET COMPANY = #{ref.company}, SYSTEM = #{ref.system}, SYSTEM_INSTANCE = #{ref.systemInstance}, TYPE = #{ref.type}, VALUE = #{ref.value} "
               + "WHERE ID = #{ref.id}")
-  void update(@Param("ref") ObjectReference ref);
+  void update(@Param("ref") ObjectReferenceImpl ref);
 
   @Delete("DELETE FROM OBJECT_REFERENCE WHERE ID = #{id}")
   void delete(String id);
+
+  @Delete(
+      "<script>DELETE FROM OBJECT_REFERENCE WHERE TASK_ID IN(<foreach item='item' collection='taskIds' separator=',' >#{item}</foreach>)</script>")
+  void deleteMultipleByTaskIds(@Param("taskIds") List<String> taskIds);
 }

lib/taskana-core/src/main/java/pro/taskana/task/internal/TaskMapper.java

@@ -56,11 +56,11 @@ public interface TaskMapper {
   @Result(property = "businessProcessId", column = "BUSINESS_PROCESS_ID")
   @Result(property = "parentBusinessProcessId", column = "PARENT_BUSINESS_PROCESS_ID")
   @Result(property = "owner", column = "OWNER")
-  @Result(property = "primaryObjRef.company", column = "POR_COMPANY")
+  @Result(property = "primaryObjRefImpl.company", column = "POR_COMPANY")
-  @Result(property = "primaryObjRef.system", column = "POR_SYSTEM")
+  @Result(property = "primaryObjRefImpl.system", column = "POR_SYSTEM")
-  @Result(property = "primaryObjRef.systemInstance", column = "POR_INSTANCE")
+  @Result(property = "primaryObjRefImpl.systemInstance", column = "POR_INSTANCE")
-  @Result(property = "primaryObjRef.type", column = "POR_TYPE")
+  @Result(property = "primaryObjRefImpl.type", column = "POR_TYPE")
-  @Result(property = "primaryObjRef.value", column = "POR_VALUE")
+  @Result(property = "primaryObjRefImpl.value", column = "POR_VALUE")
   @Result(property = "isRead", column = "IS_READ")
   @Result(property = "isTransferred", column = "IS_TRANSFERRED")
   @Result(

lib/taskana-core/src/main/java/pro/taskana/task/internal/TaskQueryImpl.java

@@ -56,6 +56,7 @@ public class TaskQueryImpl implements TaskQuery {
   private boolean selectAndClaim;
   private boolean useDistinctKeyword = false;
   private boolean joinWithAttachments = false;
+  private boolean joinWithSecondaryObjectReferences = false;
   private boolean joinWithClassifications = false;
   private boolean joinWithAttachmentClassifications = false;
   private boolean joinWithWorkbaskets = false;
@@ -255,6 +256,29 @@ public class TaskQueryImpl implements TaskQuery {
   private TimeInterval[] attachmentReceivedWithin;
   private TimeInterval[] attachmentReceivedNotWithin;
   // endregion
+  // region secondaryObjectReferences
+  private ObjectReference[] secondaryObjectReferences;
+  // endregion
+  // region secondaryObjectReferenceCompany
+  private String[] sorCompanyIn;
+  private String[] sorCompanyLike;
+  // endregion
+  // region secondaryObjectReferenceValue
+  private String[] sorValueIn;
+  private String[] sorValueLike;
+  // endregion
+  // region secondaryObjectReferenceSystem
+  private String[] sorSystemIn;
+  private String[] sorSystemLike;
+  // endregion
+  // region secondaryObjectReferenceSystemInstance
+  private String[] sorSystemInstanceIn;
+  private String[] sorSystemInstanceLike;
+  // endregion
+  // region secondaryObjectReferenceType
+  private String[] sorTypeIn;
+  private String[] sorTypeLike;
+  // endregion
   // region customAttributes
   private String[] custom1In;
   private boolean custom1InContainsNull;
@@ -1386,6 +1410,88 @@ public class TaskQueryImpl implements TaskQuery {
   public String[] getOwnerLongNameNotLike() {
     return ownerLongNameNotLike;
   }
+
+  // region secondaryObjectReference
+
+  @Override
+  public TaskQuery secondaryObjectReferenceIn(ObjectReference... objectReferences) {
+    this.joinWithSecondaryObjectReferences = true;
+    this.secondaryObjectReferences = objectReferences;
+    return this;
+  }
+
+  // endregion
+  // region secondaryObjectReferenceCompany
+  public TaskQuery sorCompanyIn(String... companyIn) {
+    joinWithSecondaryObjectReferences = true;
+    sorCompanyIn = companyIn;
+    return this;
+  }
+
+  public TaskQuery sorCompanyLike(String... companyLike) {
+    joinWithSecondaryObjectReferences = true;
+    sorCompanyLike = toUpperCopy(companyLike);
+    return this;
+  }
+
+  // endregion
+  // region secondaryObjectReferenceSystem
+  public TaskQuery sorSystemIn(String... systemIn) {
+    joinWithSecondaryObjectReferences = true;
+    sorSystemIn = systemIn;
+    return this;
+  }
+
+  public TaskQuery sorSystemLike(String... systemLike) {
+    joinWithSecondaryObjectReferences = true;
+    sorSystemLike = toUpperCopy(systemLike);
+    return this;
+  }
+
+  // endregion
+  // region secondaryObjectReferenceSystemInstance
+  public TaskQuery sorSystemInstanceIn(String... systemInstanceIn) {
+    joinWithSecondaryObjectReferences = true;
+    sorSystemInstanceIn = systemInstanceIn;
+    return this;
+  }
+
+  public TaskQuery sorSystemInstanceLike(String... systemInstanceLike) {
+    joinWithSecondaryObjectReferences = true;
+    sorSystemInstanceLike = toUpperCopy(systemInstanceLike);
+    return this;
+  }
+
+  // endregion
+  // region secondaryObjectReferenceType
+  public TaskQuery sorTypeIn(String... typeIn) {
+    joinWithSecondaryObjectReferences = true;
+    sorTypeIn = typeIn;
+    return this;
+  }
+
+  public TaskQuery sorTypeLike(String... typeLike) {
+    joinWithSecondaryObjectReferences = true;
+    sorTypeLike = toUpperCopy(typeLike);
+    return this;
+  }
+
+  // endregion
+  // region secondaryObjectReferenceValue
+  @Override
+  public TaskQuery sorValueIn(String... valueIn) {
+    joinWithSecondaryObjectReferences = true;
+    sorValueIn = valueIn;
+    return this;
+  }
+
+  public TaskQuery sorValueLike(String... valueLike) {
+    joinWithSecondaryObjectReferences = true;
+    sorValueLike = toUpperCopy(valueLike);
+    return this;
+  }
+
+  // endregion
   // region customAttributes
 
   @Override
@@ -1779,6 +1885,7 @@ public class TaskQueryImpl implements TaskQuery {
     this.wildcardSearchValueLike = wildcardSearchValue.toUpperCase();
     return this;
   }
+  // endregion
 
   @Override
   public TaskQuery wildcardSearchFieldsIn(WildcardSearchField... wildcardSearchFields) {
@@ -1886,6 +1993,10 @@ public class TaskQueryImpl implements TaskQuery {
         joinWithAttachments = true;
       }
 
+      if (columnName.isObjectReferenceColumn()) {
+        joinWithSecondaryObjectReferences = true;
+      }
+
       if (columnName == TaskQueryColumnName.OWNER_LONG_NAME) {
         joinWithUserInfo = true;
       }
@@ -1998,7 +2109,7 @@ public class TaskQueryImpl implements TaskQuery {
       joinWithAttachments = true;
       joinWithAttachmentClassifications = true;
     }
-    if (joinWithAttachments || joinWithClassifications) {
+    if (joinWithAttachments || joinWithClassifications || joinWithSecondaryObjectReferences) {
       useDistinctKeyword = true;
     }
   }
@@ -2110,6 +2221,8 @@ public class TaskQueryImpl implements TaskQuery {
         + joinWithAttachmentClassifications
         + ", joinWithWorkbaskets="
         + joinWithWorkbaskets
+        + ", joinWithSecondaryObjectReferences="
+        + joinWithSecondaryObjectReferences
         + ", addAttachmentColumnsToSelectClauseForOrdering="
         + addAttachmentColumnsToSelectClauseForOrdering
         + ", addClassificationNameToSelectClauseForOrdering="
@@ -2340,6 +2453,28 @@ public class TaskQueryImpl implements TaskQuery {
         + Arrays.toString(attachmentReceivedWithin)
         + ", attachmentReceivedNotWithin="
         + Arrays.toString(attachmentReceivedNotWithin)
+        + ", secondaryObjectReferences="
+        + Arrays.toString(secondaryObjectReferences)
+        + ", sorCompanyIn="
+        + Arrays.toString(sorCompanyIn)
+        + ", sorCompanyLike="
+        + Arrays.toString(sorCompanyLike)
+        + ", sorSystemIn="
+        + Arrays.toString(sorSystemIn)
+        + ", sorSystemNotIn="
+        + Arrays.toString(sorSystemLike)
+        + ", sorSystemNotLike="
+        + Arrays.toString(sorSystemInstanceIn)
+        + ", sorSystemInstanceLike="
+        + Arrays.toString(sorSystemInstanceLike)
+        + ", sorTypeIn="
+        + Arrays.toString(sorTypeIn)
+        + ", sorTypeLike="
+        + Arrays.toString(sorTypeLike)
+        + ", sorValueIn="
+        + Arrays.toString(sorValueIn)
+        + ", sorValueLike="
+        + Arrays.toString(sorValueLike)
         + ", custom1In="
         + Arrays.toString(custom1In)
         + ", custom1NotIn="

lib/taskana-core/src/main/java/pro/taskana/task/internal/TaskQueryMapper.java

@@ -36,11 +36,11 @@ public interface TaskQueryMapper {
   @Result(property = "parentBusinessProcessId", column = "PARENT_BUSINESS_PROCESS_ID")
   @Result(property = "owner", column = "OWNER")
   @Result(property = "ownerLongName", column = "LONG_NAME")
-  @Result(property = "primaryObjRef.company", column = "POR_COMPANY")
+  @Result(property = "primaryObjRefImpl.company", column = "POR_COMPANY")
-  @Result(property = "primaryObjRef.system", column = "POR_SYSTEM")
+  @Result(property = "primaryObjRefImpl.system", column = "POR_SYSTEM")
-  @Result(property = "primaryObjRef.systemInstance", column = "POR_INSTANCE")
+  @Result(property = "primaryObjRefImpl.systemInstance", column = "POR_INSTANCE")
-  @Result(property = "primaryObjRef.type", column = "POR_TYPE")
+  @Result(property = "primaryObjRefImpl.type", column = "POR_TYPE")
-  @Result(property = "primaryObjRef.value", column = "POR_VALUE")
+  @Result(property = "primaryObjRefImpl.value", column = "POR_VALUE")
   @Result(property = "isRead", column = "IS_READ")
   @Result(property = "isTransferred", column = "IS_TRANSFERRED")
   @Result(property = "custom1", column = "CUSTOM_1")
@@ -88,11 +88,11 @@ public interface TaskQueryMapper {
   @Result(property = "parentBusinessProcessId", column = "PARENT_BUSINESS_PROCESS_ID")
   @Result(property = "owner", column = "OWNER")
   @Result(property = "ownerLongName", column = "ULONG_NAME")
-  @Result(property = "primaryObjRef.company", column = "POR_COMPANY")
+  @Result(property = "primaryObjRefImpl.company", column = "POR_COMPANY")
-  @Result(property = "primaryObjRef.system", column = "POR_SYSTEM")
+  @Result(property = "primaryObjRefImpl.system", column = "POR_SYSTEM")
-  @Result(property = "primaryObjRef.systemInstance", column = "POR_INSTANCE")
+  @Result(property = "primaryObjRefImpl.systemInstance", column = "POR_INSTANCE")
-  @Result(property = "primaryObjRef.type", column = "POR_TYPE")
+  @Result(property = "primaryObjRefImpl.type", column = "POR_TYPE")
-  @Result(property = "primaryObjRef.value", column = "POR_VALUE")
+  @Result(property = "primaryObjRefImpl.value", column = "POR_VALUE")
   @Result(property = "isRead", column = "IS_READ")
   @Result(property = "isTransferred", column = "IS_TRANSFERRED")
   @Result(property = "custom1", column = "CUSTOM_1")

lib/taskana-core/src/main/java/pro/taskana/task/internal/TaskQuerySqlProvider.java

@@ -37,6 +37,9 @@ public class TaskQuerySqlProvider {
         + "<if test=\"joinWithAttachments\">"
         + "LEFT JOIN ATTACHMENT AS a ON t.ID = a.TASK_ID "
         + "</if>"
+        + "<if test=\"joinWithSecondaryObjectReferences\">"
+        + "LEFT JOIN OBJECT_REFERENCE AS o ON t.ID = o.TASK_ID "
+        + "</if>"
         + "<if test=\"joinWithClassifications\">"
         + "LEFT JOIN CLASSIFICATION AS c ON t.CLASSIFICATION_ID = c.ID "
         + "</if>"
@@ -83,6 +86,9 @@ public class TaskQuerySqlProvider {
         + "<if test=\"joinWithAttachments\">"
         + "LEFT JOIN ATTACHMENT a ON t.ID = a.TASK_ID "
         + "</if>"
+        + "<if test=\"joinWithSecondaryObjectReferences\">"
+        + "LEFT JOIN OBJECT_REFERENCE o ON t.ID = o.TASK_ID "
+        + "</if>"
         + "<if test=\"joinWithClassifications\">"
         + "LEFT JOIN CLASSIFICATION AS c ON t.CLASSIFICATION_ID = c.ID "
         + "</if>"
@@ -135,6 +141,9 @@ public class TaskQuerySqlProvider {
         + "<if test=\"joinWithAttachments\">"
         + "LEFT JOIN ATTACHMENT AS a ON t.ID = a.TASK_ID "
         + "</if>"
+        + "<if test=\"joinWithSecondaryObjectReferences\">"
+        + "LEFT JOIN OBJECT_REFERENCE AS o ON t.ID = o.TASK_ID "
+        + "</if>"
         + "<if test=\"joinWithClassifications\">"
         + "LEFT JOIN CLASSIFICATION AS c ON t.CLASSIFICATION_ID = c.ID "
         + "</if>"
@@ -166,6 +175,9 @@ public class TaskQuerySqlProvider {
         + "<if test=\"joinWithAttachmentClassifications\">"
         + "LEFT JOIN CLASSIFICATION AS ac ON a.CLASSIFICATION_ID = ac.ID "
         + "</if>"
+        + "<if test=\"joinWithSecondaryObjectReferences\">"
+        + "LEFT JOIN OBJECT_REFERENCE AS o ON t.ID = o.TASK_ID "
+        + "</if>"
         + "<if test=\"joinWithUserInfo\">"
         + "LEFT JOIN USER_INFO AS u ON t.owner = u.USER_ID "
         + "</if>"
@@ -199,6 +211,9 @@ public class TaskQuerySqlProvider {
         + "<if test=\"joinWithAttachmentClassifications\">"
         + "LEFT JOIN CLASSIFICATION AS ac ON a.CLASSIFICATION_ID = ac.ID "
         + "</if>"
+        + "<if test=\"joinWithSecondaryObjectReferences\">"
+        + "LEFT JOIN OBJECT_REFERENCE AS o ON t.ID = o.TASK_ID "
+        + "</if>"
         + "<if test=\"joinWithUserInfo\">"
         + "LEFT JOIN USER_INFO AS u ON t.owner = u.USER_ID "
         + "</if>"
@@ -310,6 +325,30 @@ public class TaskQuerySqlProvider {
         + "</if>";
   }
 
+  private static String commonTaskSecondaryObjectReferencesWhereStatement() {
+    return "<if test='secondaryObjectReferences != null'>"
+        + "AND (<foreach item='item' collection='secondaryObjectReferences' separator=' OR '> "
+        + "<if test='item.company != null'>o.COMPANY = #{item.company} </if>"
+        + "<if test='item.system != null'> "
+        + "<if test='item.company != null'>AND</if> "
+        + "o.SYSTEM = #{item.system} </if>"
+        + "<if test='item.systemInstance != null'> "
+        + "<if test='item.company != null or item.system != null'>AND</if> "
+        + "o.SYSTEM_INSTANCE = #{item.systemInstance} </if>"
+        + "<if test='item.type != null'> "
+        + "<if test='item.company != null or item.system != null or item.systemInstance != null'>"
+        + "AND</if> "
+        + "o.TYPE = #{item.type} </if>"
+        + "<if test='item.value != null'> "
+        + "<if test='item.company != null or item.system != null "
+        + "or item.systemInstance != null or item.type != null'>"
+        + "AND</if> "
+        + "o.VALUE = #{item.value} "
+        + "</if>"
+        + "</foreach>)"
+        + "</if>";
+  }
+
   private static void commonWhereClauses(String filter, String channel, StringBuilder sb) {
     whereIn(filter + "In", channel, sb);
     whereNotIn(filter + "NotIn", channel, sb);
@@ -337,6 +376,17 @@ public class TaskQuerySqlProvider {
     commonWhereClauses("porType", "t.POR_TYPE", sb);
     commonWhereClauses("porValue", "t.POR_VALUE", sb);
 
+    whereIn("sorCompanyIn", "o.COMPANY", sb);
+    whereLike("sorCompanyLike", "o.COMPANY", sb);
+    whereIn("sorSystemIn", "o.SYSTEM", sb);
+    whereLike("sorSystemLike", "o.SYSTEM", sb);
+    whereIn("sorSystemInstanceIn", "o.SYSTEM_INSTANCE", sb);
+    whereLike("sorSystemInstanceLike", "o.SYSTEM_INSTANCE", sb);
+    whereIn("sorTypeIn", "o.TYPE", sb);
+    whereLike("sorTypeLike", "o.TYPE", sb);
+    whereIn("sorValueIn", "o.VALUE", sb);
+    whereLike("sorValueLike", "o.VALUE", sb);
+
     whereIn("attachmentClassificationIdIn", "a.CLASSIFICATION_ID", sb);
     whereNotIn("attachmentClassificationIdNotIn", "a.CLASSIFICATION_ID", sb);
     whereIn("callbackStateIn", "t.CALLBACK_STATE", sb);
@@ -399,6 +449,7 @@ public class TaskQuerySqlProvider {
             + "</foreach>)"
             + "</if> ");
     sb.append(commonTaskObjectReferenceWhereStatement());
+    sb.append(commonTaskSecondaryObjectReferencesWhereStatement());
     return sb;
   }
 }

lib/taskana-core/src/main/java/pro/taskana/task/internal/TaskServiceImpl.java

@@ -61,6 +61,7 @@ import pro.taskana.task.api.exceptions.InvalidCallbackStateException;
 import pro.taskana.task.api.exceptions.InvalidOwnerException;
 import pro.taskana.task.api.exceptions.InvalidStateException;
 import pro.taskana.task.api.exceptions.InvalidTaskStateException;
+import pro.taskana.task.api.exceptions.ObjectReferencePersistenceException;
 import pro.taskana.task.api.exceptions.TaskAlreadyExistException;
 import pro.taskana.task.api.exceptions.TaskCommentNotFoundException;
 import pro.taskana.task.api.exceptions.TaskNotFoundException;
@@ -74,6 +75,7 @@ import pro.taskana.task.internal.ServiceLevelHandler.BulkLog;
 import pro.taskana.task.internal.models.AttachmentImpl;
 import pro.taskana.task.internal.models.AttachmentSummaryImpl;
 import pro.taskana.task.internal.models.MinimalTaskSummary;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.internal.models.TaskImpl;
 import pro.taskana.task.internal.models.TaskSummaryImpl;
 import pro.taskana.user.api.models.User;
@@ -102,6 +104,8 @@ public class TaskServiceImpl implements TaskService {
   private final ServiceLevelHandler serviceLevelHandler;
   private final AttachmentHandler attachmentHandler;
   private final AttachmentMapper attachmentMapper;
+  private final ObjectReferenceMapper objectReferenceMapper;
+  private final ObjectReferenceHandler objectReferenceHandler;
   private final UserMapper userMapper;
   private final HistoryEventManager historyEventManager;
   private final CreateTaskPreprocessorManager createTaskPreprocessorManager;
@@ -112,11 +116,13 @@ public class TaskServiceImpl implements TaskService {
       TaskMapper taskMapper,
       TaskCommentMapper taskCommentMapper,
       AttachmentMapper attachmentMapper,
+      ObjectReferenceMapper objectReferenceMapper,
       UserMapper userMapper) {
     this.taskanaEngine = taskanaEngine;
     this.taskMapper = taskMapper;
     this.workbasketService = taskanaEngine.getEngine().getWorkbasketService();
     this.attachmentMapper = attachmentMapper;
+    this.objectReferenceMapper = objectReferenceMapper;
     this.userMapper = userMapper;
     this.classificationService = taskanaEngine.getEngine().getClassificationService();
     this.historyEventManager = taskanaEngine.getHistoryEventManager();
@@ -128,6 +134,7 @@ public class TaskServiceImpl implements TaskService {
     this.serviceLevelHandler =
         new ServiceLevelHandler(taskanaEngine, taskMapper, attachmentMapper, this);
     this.attachmentHandler = new AttachmentHandler(attachmentMapper, classificationService);
+    this.objectReferenceHandler = new ObjectReferenceHandler(objectReferenceMapper);
   }
 
   @Override
@@ -175,7 +182,8 @@ public class TaskServiceImpl implements TaskService {
   @Override
   public Task createTask(Task taskToCreate)
       throws NotAuthorizedException, WorkbasketNotFoundException, ClassificationNotFoundException,
-          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException {
+          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException,
+          ObjectReferencePersistenceException {
 
     if (createTaskPreprocessorManager.isEnabled()) {
       taskToCreate = createTaskPreprocessorManager.processTaskBeforeCreation(taskToCreate);
@@ -230,7 +238,7 @@ public class TaskServiceImpl implements TaskService {
       Classification classification =
           this.classificationService.getClassification(classificationKey, workbasket.getDomain());
       task.setClassificationSummary(classification.asSummary());
-      ObjectReference.validate(task.getPrimaryObjRef(), "primary ObjectReference", "Task");
+      ObjectReferenceImpl.validate(task.getPrimaryObjRef(), "primary ObjectReference", "Task");
       standardSettingsOnTaskCreation(task, classification);
       setCallbackStateOnTaskCreation(task);
       priorityServiceManager.calculatePriorityOfTask(task).ifPresent(task::setPriority);
@@ -313,12 +321,16 @@ public class TaskServiceImpl implements TaskService {
         if (attachmentImpls == null) {
           attachmentImpls = new ArrayList<>();
         }
-
+        List<ObjectReferenceImpl> secondaryObjectReferences =
+            objectReferenceMapper.findObjectReferencesByTaskId(resultTask.getId());
+        if (secondaryObjectReferences == null) {
+          secondaryObjectReferences = new ArrayList<>();
+        }
         Map<String, ClassificationSummary> classificationSummariesById =
             findClassificationForTaskImplAndAttachments(resultTask, attachmentImpls);
         addClassificationSummariesToAttachments(attachmentImpls, classificationSummariesById);
         resultTask.setAttachments(new ArrayList<>(attachmentImpls));
-
+        resultTask.setSecondaryObjectReferences(new ArrayList<>(secondaryObjectReferences));
         String classificationId = resultTask.getClassificationSummary().getId();
         ClassificationSummary classification = classificationSummariesById.get(classificationId);
         if (classification == null) {
@@ -423,10 +435,22 @@ public class TaskServiceImpl implements TaskService {
     return new AttachmentImpl();
   }
 
+  @Override
+  public ObjectReference newObjectReference() {
+    return new ObjectReferenceImpl();
+  }
+
+  @Override
+  public ObjectReference newObjectReference(
+      String company, String system, String systemInstance, String type, String value) {
+    return new ObjectReferenceImpl(company, system, systemInstance, type, value);
+  }
+
   @Override
   public Task updateTask(Task task)
       throws InvalidArgumentException, TaskNotFoundException, ConcurrencyException,
-          NotAuthorizedException, AttachmentPersistenceException, InvalidStateException,
+          NotAuthorizedException, AttachmentPersistenceException,
+          ObjectReferencePersistenceException, InvalidStateException,
           ClassificationNotFoundException {
     String userId = taskanaEngine.getEngine().getCurrentUserContext().getUserid();
     TaskImpl newTaskImpl = (TaskImpl) task;
@@ -437,7 +461,9 @@ public class TaskServiceImpl implements TaskService {
       checkConcurrencyAndSetModified(newTaskImpl, oldTaskImpl);
 
       attachmentHandler.insertAndDeleteAttachmentsOnTaskUpdate(newTaskImpl, oldTaskImpl);
-      ObjectReference.validate(newTaskImpl.getPrimaryObjRef(), "primary ObjectReference", "Task");
+      objectReferenceHandler.insertAndDeleteObjectReferencesOnTaskUpdate(newTaskImpl, oldTaskImpl);
+      ObjectReferenceImpl.validate(
+          newTaskImpl.getPrimaryObjRef(), "primary ObjectReference", "Task");
 
       standardUpdateActions(oldTaskImpl, newTaskImpl);
 
@@ -555,6 +581,7 @@ public class TaskServiceImpl implements TaskService {
 
       if (!taskIds.isEmpty()) {
         attachmentMapper.deleteMultipleByTaskIds(taskIds);
+        objectReferenceMapper.deleteMultipleByTaskIds(taskIds);
         taskMapper.deleteMultiple(taskIds);
 
         if (taskanaEngine.getEngine().isHistoryEnabled()
@@ -588,7 +615,7 @@ public class TaskServiceImpl implements TaskService {
       ObjectReference selectionCriteria, Map<TaskCustomField, String> customFieldsToUpdate)
       throws InvalidArgumentException {
 
-    ObjectReference.validate(selectionCriteria, "ObjectReference", "updateTasks call");
+    ObjectReferenceImpl.validate(selectionCriteria, "ObjectReference", "updateTasks call");
     validateCustomFields(customFieldsToUpdate);
     TaskCustomPropertySelector fieldSelector = new TaskCustomPropertySelector();
     TaskImpl updated = initUpdatedTask(customFieldsToUpdate, fieldSelector);
@@ -952,7 +979,7 @@ public class TaskServiceImpl implements TaskService {
     // splitting Augmentation into steps of maximal 32000 tasks
     // reason: DB2 has a maximum for parameters in a query
     return CollectionUtil.partitionBasedOnSize(taskSummaries, 32000).stream()
-        .map(this::augmentTaskSummariesByContainedSummariesWithoutPartitioning)
+        .map(this::appendComplexAttributesToTaskSummariesWithoutPartitioning)
         .flatMap(Collection::stream)
         .collect(Collectors.toList());
   }
@@ -975,7 +1002,7 @@ public class TaskServiceImpl implements TaskService {
     return Pair.of(filteredTasks, bulkLog);
   }
 
-  private List<TaskSummaryImpl> augmentTaskSummariesByContainedSummariesWithoutPartitioning(
+  private List<TaskSummaryImpl> appendComplexAttributesToTaskSummariesWithoutPartitioning(
       List<TaskSummaryImpl> taskSummaries) {
     Set<String> taskIds =
         taskSummaries.stream().map(TaskSummaryImpl::getId).collect(Collectors.toSet());
@@ -995,12 +1022,15 @@ public class TaskServiceImpl implements TaskService {
         attachmentMapper.findAttachmentSummariesByTaskIds(taskIds);
     Map<String, ClassificationSummary> classificationSummariesById =
         findClassificationsForTasksAndAttachments(taskSummaries, attachmentSummaries);
-    Map<String, WorkbasketSummary> workbasketSummariesById = findWorkbasketsForTasks(taskSummaries);
-
     addClassificationSummariesToAttachments(attachmentSummaries, classificationSummariesById);
     addClassificationSummariesToTaskSummaries(taskSummaries, classificationSummariesById);
-    addWorkbasketSummariesToTaskSummaries(taskSummaries, workbasketSummariesById);
     addAttachmentSummariesToTaskSummaries(taskSummaries, attachmentSummaries);
+    Map<String, WorkbasketSummary> workbasketSummariesById = findWorkbasketsForTasks(taskSummaries);
+    List<ObjectReferenceImpl> objectReferences =
+        objectReferenceMapper.findObjectReferencesByTaskIds(taskIds);
+
+    addWorkbasketSummariesToTaskSummaries(taskSummaries, workbasketSummariesById);
+    addObjectReferencesToTaskSummaries(taskSummaries, objectReferences);
 
     return taskSummaries;
   }
@@ -1306,6 +1336,7 @@ public class TaskServiceImpl implements TaskService {
       }
 
       attachmentMapper.deleteMultipleByTaskIds(Collections.singletonList(taskId));
+      objectReferenceMapper.deleteMultipleByTaskIds(Collections.singletonList(taskId));
       taskMapper.delete(taskId);
 
       if (taskanaEngine.getEngine().isHistoryEnabled()
@@ -1443,7 +1474,7 @@ public class TaskServiceImpl implements TaskService {
 
   private void standardSettingsOnTaskCreation(TaskImpl task, Classification classification)
       throws InvalidArgumentException, ClassificationNotFoundException,
-          AttachmentPersistenceException {
+          AttachmentPersistenceException, ObjectReferencePersistenceException {
     final Instant now = Instant.now();
     task.setId(IdGenerator.generateWithPrefix(IdGenerator.ID_PREFIX_TASK));
     if (task.getExternalId() == null) {
@@ -1480,6 +1511,7 @@ public class TaskServiceImpl implements TaskService {
     setDefaultTaskReceivedDateFromAttachments(task);
 
     attachmentHandler.insertNewAttachmentsOnTaskCreation(task);
+    objectReferenceHandler.insertNewSecondaryObjectReferencesOnTaskCreation(task);
     // This has to be called after the AttachmentHandler because the AttachmentHandler fetches
     // the Classifications of the Attachments.
     // This is necessary to guarantee that the following calculation is correct.
@@ -1706,6 +1738,32 @@ public class TaskServiceImpl implements TaskService {
     }
   }
 
+  private void addObjectReferencesToTaskSummaries(
+      List<TaskSummaryImpl> taskSummaries, List<ObjectReferenceImpl> objectReferences) {
+    if (taskSummaries == null || taskSummaries.isEmpty()) {
+      return;
+    }
+
+    Map<String, TaskSummaryImpl> taskSummariesById =
+        taskSummaries.stream()
+            .collect(
+                Collectors.toMap(
+                    TaskSummary::getId,
+                    Function.identity(),
+                    // The TaskQuery#list function
+                    // returns the same task multiple times when that task has more than one
+                    // object reference...Therefore, this MergeFunction is necessary.
+                    (a, b) -> b));
+
+    for (ObjectReferenceImpl objectReference : objectReferences) {
+      String taskId = objectReference.getTaskId();
+      TaskSummaryImpl taskSummary = taskSummariesById.get(taskId);
+      if (taskSummary != null) {
+        taskSummary.addSecondaryObjectReference(objectReference);
+      }
+    }
+  }
+
   private TaskImpl initUpdatedTask(
       Map<TaskCustomField, String> customFieldsToUpdate, TaskCustomPropertySelector fieldSelector) {
 

lib/taskana-core/src/main/java/pro/taskana/task/internal/builder/ObjectReferenceBuilder.java

@@ -1,10 +1,11 @@
 package pro.taskana.task.internal.builder;
 
 import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 
 public class ObjectReferenceBuilder {
 
-  private final ObjectReference objectReference = new ObjectReference();
+  private final ObjectReferenceImpl objectReference = new ObjectReferenceImpl();
 
   private ObjectReferenceBuilder() {}
 

lib/taskana-core/src/main/java/pro/taskana/task/internal/builder/TaskBuilder.java

@@ -17,6 +17,7 @@ import pro.taskana.task.api.TaskCustomField;
 import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.TaskState;
 import pro.taskana.task.api.exceptions.AttachmentPersistenceException;
+import pro.taskana.task.api.exceptions.ObjectReferencePersistenceException;
 import pro.taskana.task.api.exceptions.TaskAlreadyExistException;
 import pro.taskana.task.api.exceptions.TaskNotFoundException;
 import pro.taskana.task.api.models.Attachment;
@@ -168,6 +169,11 @@ public class TaskBuilder {
     return this;
   }
 
+  public TaskBuilder objectReferences(ObjectReference... objectReferences) {
+    testTask.setSecondaryObjectReferences(Arrays.asList(objectReferences));
+    return this;
+  }
+
   public TaskBuilder customAttribute(TaskCustomField customField, String value) {
     testTask.setCustomAttribute(customField, value);
     return this;
@@ -196,7 +202,7 @@ public class TaskBuilder {
   public Task buildAndStore(TaskService taskService)
       throws TaskAlreadyExistException, InvalidArgumentException, WorkbasketNotFoundException,
           ClassificationNotFoundException, NotAuthorizedException, AttachmentPersistenceException,
-          TaskNotFoundException {
+          ObjectReferencePersistenceException, TaskNotFoundException {
     try {
       Task task = taskService.createTask(testTask);
       return taskService.getTask(task.getId());
@@ -218,7 +224,7 @@ public class TaskBuilder {
   public TaskSummary buildAndStoreAsSummary(TaskService taskService)
       throws TaskAlreadyExistException, InvalidArgumentException, TaskNotFoundException,
           WorkbasketNotFoundException, ClassificationNotFoundException, NotAuthorizedException,
-          AttachmentPersistenceException {
+          AttachmentPersistenceException, ObjectReferencePersistenceException {
     return buildAndStore(taskService).asSummary();
   }
 

lib/taskana-core/src/main/java/pro/taskana/task/internal/models/AttachmentSummaryImpl.java

@@ -121,6 +121,16 @@ public class AttachmentSummaryImpl implements AttachmentSummary {
     this.classificationSummary = classificationSummary;
   }
 
+  // auxiliary method to enable MyBatis access to objectReference
+  public ObjectReferenceImpl getObjectReferenceImpl() {
+    return (ObjectReferenceImpl) objectReference;
+  }
+
+  // auxiliary method to enable MyBatis access to objectReference
+  public void setObjectReferenceImpl(ObjectReferenceImpl objectReferenceImpl) {
+    this.objectReference = objectReferenceImpl;
+  }
+
   protected boolean canEqual(Object other) {
     return (!(other instanceof AttachmentSummaryImpl));
   }

lib/taskana-core/src/main/java/pro/taskana/task/internal/models/ObjectReferenceImpl.java

@@ -0,0 +1,165 @@
+package pro.taskana.task.internal.models;
+
+import java.util.Objects;
+
+import pro.taskana.common.api.exceptions.InvalidArgumentException;
+import pro.taskana.task.api.models.ObjectReference;
+
+/** ObjectReference entity. */
+public class ObjectReferenceImpl implements ObjectReference {
+  private String id;
+  private String taskId;
+  private String company;
+  private String system;
+  private String systemInstance;
+  private String type;
+  private String value;
+
+  public ObjectReferenceImpl() {}
+
+  public ObjectReferenceImpl(
+      String company, String system, String systemInstance, String type, String value) {
+    this.company = company;
+    this.system = system;
+    this.systemInstance = systemInstance;
+    this.type = type;
+    this.value = value;
+  }
+
+  private ObjectReferenceImpl(ObjectReferenceImpl copyFrom) {
+    company = copyFrom.company;
+    system = copyFrom.system;
+    systemInstance = copyFrom.systemInstance;
+    type = copyFrom.type;
+    value = copyFrom.value;
+  }
+
+  @Override
+  public String getId() {
+    return id;
+  }
+
+  public void setId(String id) {
+    this.id = id;
+  }
+
+  @Override
+  public String getTaskId() {
+    return taskId;
+  }
+
+  public void setTaskId(String taskId) {
+    this.taskId = taskId;
+  }
+
+  @Override
+  public String getCompany() {
+    return company;
+  }
+
+  public void setCompany(String company) {
+    this.company = company;
+  }
+
+  @Override
+  public String getSystem() {
+    return system;
+  }
+
+  public void setSystem(String system) {
+    this.system = system;
+  }
+
+  @Override
+  public String getSystemInstance() {
+    return systemInstance;
+  }
+
+  public void setSystemInstance(String systemInstance) {
+    this.systemInstance = systemInstance;
+  }
+
+  @Override
+  public String getType() {
+    return type;
+  }
+
+  public void setType(String type) {
+    this.type = type;
+  }
+
+  @Override
+  public String getValue() {
+    return value;
+  }
+
+  public void setValue(String value) {
+    this.value = value;
+  }
+
+  @Override
+  public ObjectReferenceImpl copy() {
+    return new ObjectReferenceImpl(this);
+  }
+
+  public static void validate(ObjectReference objectReference, String objRefType, String objName)
+      throws InvalidArgumentException {
+    // check that all values in the ObjectReference are set correctly
+    if (objectReference == null) {
+      throw new InvalidArgumentException(
+          String.format("%s of %s must not be null.", objRefType, objName));
+    } else if (objectReference.getCompany() == null || objectReference.getCompany().isEmpty()) {
+      throw new InvalidArgumentException(
+          String.format("Company of %s of %s must not be empty", objRefType, objName));
+    } else if (objectReference.getType() == null || objectReference.getType().length() == 0) {
+      throw new InvalidArgumentException(
+          String.format("Type of %s of %s must not be empty", objRefType, objName));
+    } else if (objectReference.getValue() == null || objectReference.getValue().length() == 0) {
+      throw new InvalidArgumentException(
+          String.format("Value of %s of %s must not be empty", objRefType, objName));
+    }
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(id, taskId, company, system, systemInstance, type, value);
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (!(obj instanceof ObjectReferenceImpl)) {
+      return false;
+    }
+    ObjectReferenceImpl other = (ObjectReferenceImpl) obj;
+    return Objects.equals(id, other.id)
+        && Objects.equals(taskId, other.taskId)
+        && Objects.equals(company, other.company)
+        && Objects.equals(system, other.system)
+        && Objects.equals(systemInstance, other.systemInstance)
+        && Objects.equals(type, other.type)
+        && Objects.equals(value, other.value);
+  }
+
+  @Override
+  public String toString() {
+    return "ObjectReference ["
+        + "id="
+        + this.id
+        + ", taskId="
+        + this.taskId
+        + ", company="
+        + this.company
+        + ", system="
+        + this.system
+        + ", systemInstance="
+        + this.systemInstance
+        + ", type="
+        + this.type
+        + ", value="
+        + this.value
+        + "]";
+  }
+}

lib/taskana-core/src/main/java/pro/taskana/task/internal/models/TaskImpl.java

@@ -201,6 +201,7 @@ public class TaskImpl extends TaskSummaryImpl implements Task {
       attSummaries.add(att.asSummary());
     }
     taskSummary.setAttachmentSummaries(attSummaries);
+    taskSummary.setSecondaryObjectReferences(secondaryObjectReferences);
     taskSummary.setBusinessProcessId(this.businessProcessId);
     taskSummary.setClaimed(claimed);
     if (classificationSummary != null) {
@@ -313,6 +314,8 @@ public class TaskImpl extends TaskSummaryImpl implements Task {
         + callbackState
         + ", attachments="
         + attachments
+        + ", objectReferences="
+        + secondaryObjectReferences
         + ", id="
         + id
         + ", externalId="

lib/taskana-core/src/main/java/pro/taskana/task/internal/models/TaskSummaryImpl.java

@@ -5,6 +5,7 @@ import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import java.util.stream.Collectors;
 
 import pro.taskana.classification.api.models.ClassificationSummary;
 import pro.taskana.classification.internal.models.ClassificationSummaryImpl;
@@ -46,6 +47,7 @@ public class TaskSummaryImpl implements TaskSummary {
   protected boolean isTransferred;
   // All objects have to be serializable
   protected List<AttachmentSummary> attachmentSummaries = new ArrayList<>();
+  protected List<ObjectReference> secondaryObjectReferences = new ArrayList<>();
   protected String custom1;
   protected String custom2;
   protected String custom3;
@@ -88,6 +90,10 @@ public class TaskSummaryImpl implements TaskSummary {
     isRead = copyFrom.isRead;
     isTransferred = copyFrom.isTransferred;
     attachmentSummaries = new ArrayList<>(copyFrom.attachmentSummaries);
+    secondaryObjectReferences =
+        copyFrom.secondaryObjectReferences.stream()
+            .map(ObjectReference::copy)
+            .collect(Collectors.toList());
     custom1 = copyFrom.custom1;
     custom2 = copyFrom.custom2;
     custom3 = copyFrom.custom3;
@@ -268,6 +274,15 @@ public class TaskSummaryImpl implements TaskSummary {
     this.attachmentSummaries = attachmentSummaries;
   }
 
+  @Override
+  public List<ObjectReference> getSecondaryObjectReferences() {
+    return secondaryObjectReferences;
+  }
+
+  public void setSecondaryObjectReferences(List<ObjectReference> objectReferences) {
+    this.secondaryObjectReferences = objectReferences;
+  }
+
   @Override
   public String getDomain() {
     return workbasketSummary == null ? null : workbasketSummary.getDomain();
@@ -325,6 +340,11 @@ public class TaskSummaryImpl implements TaskSummary {
     this.primaryObjRef = primaryObjRef;
   }
 
+  public void setPrimaryObjRef(
+      String company, String system, String systemInstance, String type, String value) {
+    this.primaryObjRef = new ObjectReferenceImpl(company, system, systemInstance, type, value);
+  }
+
   @Override
   public boolean isRead() {
     return isRead;
@@ -406,6 +426,50 @@ public class TaskSummaryImpl implements TaskSummary {
     this.attachmentSummaries.add(attachmentSummary);
   }
 
+  @Override
+  public void addSecondaryObjectReference(ObjectReference objectReferenceToAdd) {
+    if (secondaryObjectReferences == null) {
+      secondaryObjectReferences = new ArrayList<>();
+    }
+    if (objectReferenceToAdd != null) {
+      ((ObjectReferenceImpl) objectReferenceToAdd).setTaskId(this.id);
+      if (objectReferenceToAdd.getId() != null) {
+        secondaryObjectReferences.removeIf(
+            objectReference -> objectReferenceToAdd.getId().equals(objectReference.getId()));
+      }
+      secondaryObjectReferences.add(objectReferenceToAdd);
+    }
+  }
+
+  @Override
+  public void addSecondaryObjectReference(
+      String company, String system, String systemInstance, String type, String value) {
+    ObjectReferenceImpl objectReferenceToAdd =
+        new ObjectReferenceImpl(company, system, systemInstance, type, value);
+    if (secondaryObjectReferences == null) {
+      secondaryObjectReferences = new ArrayList<>();
+    }
+    objectReferenceToAdd.setTaskId(this.id);
+    if (objectReferenceToAdd.getId() != null) {
+      secondaryObjectReferences.removeIf(
+          objectReference -> objectReferenceToAdd.getId().equals(objectReference.getId()));
+    }
+    secondaryObjectReferences.add(objectReferenceToAdd);
+  }
+
+  @Override
+  public ObjectReference removeSecondaryObjectReference(String objectReferenceId) {
+    ObjectReference result = null;
+    for (ObjectReference objectReference : secondaryObjectReferences) {
+      if (objectReference.getId().equals(objectReferenceId)
+          && secondaryObjectReferences.remove(objectReference)) {
+        result = objectReference;
+        break;
+      }
+    }
+    return result;
+  }
+
   // auxiliary Method to enable Mybatis to access classificationSummary
   public ClassificationSummaryImpl getClassificationSummaryImpl() {
     return (ClassificationSummaryImpl) classificationSummary;
@@ -416,6 +480,16 @@ public class TaskSummaryImpl implements TaskSummary {
     setClassificationSummary(classificationSummary);
   }
 
+  // auxiliary Method to enable Mybatis to access primaryObjRef
+  public ObjectReferenceImpl getPrimaryObjRefImpl() {
+    return (ObjectReferenceImpl) primaryObjRef;
+  }
+
+  // auxiliary Method to enable Mybatis to access primaryObjRef
+  public void setPrimaryObjRefImpl(ObjectReferenceImpl objectReference) {
+    setPrimaryObjRef(objectReference);
+  }
+
   public String getCustom1() {
     return custom1;
   }
@@ -592,6 +666,7 @@ public class TaskSummaryImpl implements TaskSummary {
         isRead,
         isTransferred,
         attachmentSummaries,
+        secondaryObjectReferences,
         custom1,
         custom2,
         custom3,
@@ -647,6 +722,7 @@ public class TaskSummaryImpl implements TaskSummary {
         && Objects.equals(ownerLongName, other.ownerLongName)
         && Objects.equals(primaryObjRef, other.primaryObjRef)
         && Objects.equals(attachmentSummaries, other.attachmentSummaries)
+        && Objects.equals(secondaryObjectReferences, other.secondaryObjectReferences)
         && Objects.equals(custom1, other.custom1)
         && Objects.equals(custom2, other.custom2)
         && Objects.equals(custom3, other.custom3)
@@ -717,6 +793,8 @@ public class TaskSummaryImpl implements TaskSummary {
         + isTransferred
         + ", attachmentSummaries="
         + attachmentSummaries
+        + ", objectReferences="
+        + secondaryObjectReferences
         + ", custom1="
         + custom1
         + ", custom2="

lib/taskana-core/src/test/java/acceptance/AbstractAccTest.java

@@ -27,6 +27,7 @@ import pro.taskana.sampledata.SampleDataGenerator;
 import pro.taskana.task.api.models.Attachment;
 import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.internal.TaskServiceImpl;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.user.api.models.User;
 
 /** Base class for all acceptance tests. */
@@ -78,9 +79,9 @@ public abstract class AbstractAccTest {
     return sqlSessionManager.getMapper(JobMapper.class);
   }
 
-  protected ObjectReference createObjectReference(
+  protected ObjectReferenceImpl createObjectReference(
       String company, String system, String systemInstance, String type, String value) {
-    ObjectReference objectReference = new ObjectReference();
+    ObjectReferenceImpl objectReference = new ObjectReferenceImpl();
     objectReference.setCompany(company);
     objectReference.setSystem(system);
     objectReference.setSystemInstance(systemInstance);

lib/taskana-core/src/test/java/acceptance/TaskTestMapper.java

@@ -54,11 +54,11 @@ public interface TaskTestMapper {
         @Result(property = "businessProcessId", column = "BUSINESS_PROCESS_ID"),
         @Result(property = "parentBusinessProcessId", column = "PARENT_BUSINESS_PROCESS_ID"),
         @Result(property = "owner", column = "OWNER"),
-        @Result(property = "primaryObjRef.company", column = "POR_COMPANY"),
+        @Result(property = "primaryObjRefImpl.company", column = "POR_COMPANY"),
-        @Result(property = "primaryObjRef.system", column = "POR_SYSTEM"),
+        @Result(property = "primaryObjRefImpl.system", column = "POR_SYSTEM"),
-        @Result(property = "primaryObjRef.systemInstance", column = "POR_INSTANCE"),
+        @Result(property = "primaryObjRefImpl.systemInstance", column = "POR_INSTANCE"),
-        @Result(property = "primaryObjRef.type", column = "POR_TYPE"),
+        @Result(property = "primaryObjRefImpl.type", column = "POR_TYPE"),
-        @Result(property = "primaryObjRef.value", column = "POR_VALUE"),
+        @Result(property = "primaryObjRefImpl.value", column = "POR_VALUE"),
         @Result(property = "isRead", column = "IS_READ"),
         @Result(property = "isTransferred", column = "IS_TRANSFERRED"),
         @Result(

lib/taskana-core/src/test/java/acceptance/builder/ObjectReferenceBuilderTest.java

@@ -6,6 +6,7 @@ import static pro.taskana.task.internal.builder.ObjectReferenceBuilder.newObject
 import org.junit.jupiter.api.Test;
 
 import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 
 class ObjectReferenceBuilderTest {
 
@@ -20,7 +21,7 @@ class ObjectReferenceBuilderTest {
             .value("Value1")
             .build();
 
-    ObjectReference expectedObjectReference = new ObjectReference();
+    ObjectReferenceImpl expectedObjectReference = new ObjectReferenceImpl();
     expectedObjectReference.setCompany("Company1");
     expectedObjectReference.setSystem("System1");
     expectedObjectReference.setSystemInstance("Instance1");
@@ -28,7 +29,7 @@ class ObjectReferenceBuilderTest {
     expectedObjectReference.setValue("Value1");
 
     assertThat(objectReference)
-        .hasNoNullFieldsOrPropertiesExcept("id")
+        .hasNoNullFieldsOrPropertiesExcept("id", "taskId")
         .isEqualTo(expectedObjectReference);
   }
 }

lib/taskana-core/src/test/java/acceptance/task/CreateTaskAccTest.java

@@ -37,6 +37,7 @@ import pro.taskana.task.api.models.AttachmentSummary;
 import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
 import pro.taskana.task.internal.AttachmentMapper;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.internal.models.TaskImpl;
 import pro.taskana.workbasket.api.WorkbasketService;
 import pro.taskana.workbasket.api.exceptions.WorkbasketNotFoundException;
@@ -79,11 +80,14 @@ class CreateTaskAccTest extends AbstractAccTest {
 
     Task newTask = taskService.newTask("USER-1-1", "DOMAIN_A");
     newTask.setClassificationKey("T2100");
-    ObjectReference objectReference =
+    ObjectReferenceImpl objectReference =
         createObjectReference("COMPANY_A", "SYSTEM_A", "INSTANCE_A", "VNR", "1234567");
+    objectReference.setTaskId(newTask.getId());
     newTask.setPrimaryObjRef(objectReference);
+
     newTask.setOwner("user-1-1");
     Task createdTask = taskService.createTask(newTask);
+
     Instant expectedPlanned = moveForwardToWorkingDay(createdTask.getCreated());
 
     assertThat(createdTask).isNotNull();

lib/taskana-core/src/test/java/acceptance/task/CreateTaskWithSorAccTest.java

@@ -0,0 +1,176 @@
+package acceptance.task;
+
+import static acceptance.DefaultTestEntities.defaultTestClassification;
+import static acceptance.DefaultTestEntities.defaultTestObjectReference;
+import static acceptance.DefaultTestEntities.defaultTestWorkbasket;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import acceptance.TaskanaEngineProxy;
+import java.util.stream.Collectors;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import testapi.TaskanaInject;
+import testapi.TaskanaIntegrationTest;
+
+import pro.taskana.classification.api.ClassificationService;
+import pro.taskana.classification.api.models.ClassificationSummary;
+import pro.taskana.common.api.TaskanaEngine;
+import pro.taskana.common.api.exceptions.InvalidArgumentException;
+import pro.taskana.common.test.security.WithAccessId;
+import pro.taskana.task.api.TaskService;
+import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.ObjectReferenceMapper;
+import pro.taskana.task.internal.builder.ObjectReferenceBuilder;
+import pro.taskana.task.internal.builder.TaskBuilder;
+import pro.taskana.task.internal.models.TaskImpl;
+import pro.taskana.workbasket.api.WorkbasketPermission;
+import pro.taskana.workbasket.api.WorkbasketService;
+import pro.taskana.workbasket.api.models.WorkbasketSummary;
+import pro.taskana.workbasket.internal.builder.WorkbasketAccessItemBuilder;
+
+/**
+ * Acceptance test for all "create task" scenarios that involve secondary {@link ObjectReference}.
+ */
+@TaskanaIntegrationTest
+class CreateTaskWithSorAccTest {
+  @TaskanaInject TaskService taskService;
+  @TaskanaInject WorkbasketService workbasketService;
+  @TaskanaInject ClassificationService classificationService;
+  @TaskanaInject TaskanaEngine taskanaEngine;
+
+  ClassificationSummary defaultClassificationSummary;
+  WorkbasketSummary defaultWorkbasketSummary;
+  ObjectReference defaultObjectReference;
+
+  @WithAccessId(user = "businessadmin")
+  @BeforeAll
+  void setup() throws Exception {
+    defaultClassificationSummary =
+        defaultTestClassification().buildAndStoreAsSummary(classificationService);
+    defaultWorkbasketSummary = defaultTestWorkbasket().buildAndStoreAsSummary(workbasketService);
+
+    WorkbasketAccessItemBuilder.newWorkbasketAccessItem()
+        .workbasketId(defaultWorkbasketSummary.getId())
+        .accessId("user-1-1")
+        .permission(WorkbasketPermission.OPEN)
+        .permission(WorkbasketPermission.READ)
+        .permission(WorkbasketPermission.APPEND)
+        .buildAndStore(workbasketService);
+    defaultObjectReference = defaultTestObjectReference().build();
+  }
+
+  @WithAccessId(user = "user-1-1")
+  @Test
+  void should_createObjectReferences_When_CreatingTask() throws Exception {
+    Task task = taskService.newTask(defaultWorkbasketSummary.getId());
+    task.setClassificationKey(defaultClassificationSummary.getKey());
+    task.setPrimaryObjRef(defaultObjectReference);
+
+    ObjectReference sor1 =
+        taskService.newObjectReference(
+            "FirstCompany", "FirstSystem", null, "FirstType", "FirstValue");
+    ObjectReference sor2 =
+        taskService.newObjectReference("SecondCompany", null, null, "SecondType", "SecondValue");
+
+    task.addSecondaryObjectReference(sor1);
+    task.addSecondaryObjectReference(sor2);
+
+    Task createdTask = taskService.createTask(task);
+
+    TaskanaEngineProxy engineProxy = new TaskanaEngineProxy(taskanaEngine);
+    ObjectReferenceMapper objectReferenceMapper =
+        engineProxy.getEngine().getSqlSession().getMapper(ObjectReferenceMapper.class);
+
+    try {
+      engineProxy.openConnection();
+      assertThat(objectReferenceMapper.findObjectReferencesByTaskId(createdTask.getId()))
+          .hasSize(2);
+    } finally {
+      engineProxy.returnConnection();
+    }
+
+    Task readTask = taskService.getTask(createdTask.getId());
+
+    assertThat(readTask.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getSystem)
+        .containsExactly("FirstSystem", null);
+
+    assertThat(readTask.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getType)
+        .containsExactly("FirstType", "SecondType");
+
+    assertThat(readTask.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getValue)
+        .containsExactly("FirstValue", "SecondValue");
+
+    assertThat(readTask.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getCompany)
+        .containsExactly("FirstCompany", "SecondCompany");
+  }
+
+  @WithAccessId(user = "user-1-1")
+  @Test
+  void should_ThrowException_When_InvalidObjectReference() throws Exception {
+    ObjectReference sor1 =
+        taskService.newObjectReference(
+            "FirstCompany", "FirstSystem", null, "FirstType", "FirstValue");
+    ObjectReference invalidSor =
+        taskService.newObjectReference(null, null, null, "Second Type", "Second Value");
+
+    TaskImpl task = (TaskImpl) taskService.newTask(defaultWorkbasketSummary.getId());
+    task.setClassificationKey(defaultClassificationSummary.getKey());
+    task.setPrimaryObjRef(defaultObjectReference);
+    task.addSecondaryObjectReference(sor1);
+    task.addSecondaryObjectReference(invalidSor);
+    assertThatThrownBy(() -> taskService.createTask(task))
+        .isInstanceOf(InvalidArgumentException.class)
+        .hasMessage("Company of ObjectReference of Task must not be empty");
+  }
+
+  @WithAccessId(user = "user-1-1")
+  @Test
+  void should_copyObjectReferences_When_DuplicatingTask() throws Exception {
+    ObjectReference sor1 =
+        ObjectReferenceBuilder.newObjectReference()
+            .company("FirstCompany")
+            .value("FirstValue")
+            .type("FirstType")
+            .build();
+    ObjectReference sor2 =
+        ObjectReferenceBuilder.newObjectReference()
+            .company("SecondCompany")
+            .value("SecondValue")
+            .type("SecondType")
+            .build();
+    Task oldTask =
+        TaskBuilder.newTask()
+            .classificationSummary(defaultClassificationSummary)
+            .workbasketSummary(defaultWorkbasketSummary)
+            .primaryObjRef(defaultObjectReference)
+            .objectReferences(sor1, sor2)
+            .buildAndStore(taskService);
+    Task newTask = oldTask.copy();
+    newTask = taskService.createTask(newTask);
+
+    Task readOldTask = taskService.getTask(oldTask.getId());
+
+    assertThat(readOldTask.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getTaskId)
+        .containsExactly(oldTask.getId(), oldTask.getId());
+
+    Task readNewTask = taskService.getTask(newTask.getId());
+
+    assertThat(readNewTask.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getTaskId)
+        .containsExactly(newTask.getId(), newTask.getId());
+
+    assertThat(readNewTask.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getId)
+        .doesNotContainAnyElementsOf(
+            readOldTask.getSecondaryObjectReferences().stream()
+                .map(ObjectReference::getTaskId)
+                .collect(Collectors.toList()));
+  }
+}

lib/taskana-core/src/test/java/acceptance/task/DeleteTaskWithSorAccTest.java

@@ -0,0 +1,123 @@
+package acceptance.task;
+
+import static acceptance.DefaultTestEntities.defaultTestClassification;
+import static acceptance.DefaultTestEntities.defaultTestObjectReference;
+import static acceptance.DefaultTestEntities.defaultTestWorkbasket;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import acceptance.TaskanaEngineProxy;
+import java.util.List;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import testapi.TaskanaInject;
+import testapi.TaskanaIntegrationTest;
+
+import pro.taskana.classification.api.ClassificationService;
+import pro.taskana.classification.api.models.ClassificationSummary;
+import pro.taskana.common.api.TaskanaEngine;
+import pro.taskana.common.test.security.WithAccessId;
+import pro.taskana.task.api.TaskService;
+import pro.taskana.task.api.TaskState;
+import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.ObjectReferenceMapper;
+import pro.taskana.task.internal.builder.ObjectReferenceBuilder;
+import pro.taskana.task.internal.builder.TaskBuilder;
+import pro.taskana.workbasket.api.WorkbasketPermission;
+import pro.taskana.workbasket.api.WorkbasketService;
+import pro.taskana.workbasket.api.models.WorkbasketSummary;
+import pro.taskana.workbasket.internal.builder.WorkbasketAccessItemBuilder;
+
+/**
+ * Acceptance test for all "delete task" scenarios that involve secondary {@link ObjectReference}s.
+ */
+@TaskanaIntegrationTest
+class DeleteTaskWithSorAccTest {
+  @TaskanaInject TaskService taskService;
+  @TaskanaInject WorkbasketService workbasketService;
+  @TaskanaInject ClassificationService classificationService;
+  @TaskanaInject TaskanaEngine taskanaEngine;
+
+  ClassificationSummary defaultClassificationSummary;
+  WorkbasketSummary defaultWorkbasketSummary;
+  ObjectReference defaultObjectReference;
+  ObjectReference sor1;
+  ObjectReference sor2;
+
+  @WithAccessId(user = "businessadmin")
+  @BeforeAll
+  void setup() throws Exception {
+    defaultClassificationSummary =
+        defaultTestClassification().buildAndStoreAsSummary(classificationService);
+    defaultWorkbasketSummary = defaultTestWorkbasket().buildAndStoreAsSummary(workbasketService);
+
+    WorkbasketAccessItemBuilder.newWorkbasketAccessItem()
+        .workbasketId(defaultWorkbasketSummary.getId())
+        .accessId("user-1-1")
+        .permission(WorkbasketPermission.OPEN)
+        .permission(WorkbasketPermission.READ)
+        .permission(WorkbasketPermission.APPEND)
+        .buildAndStore(workbasketService);
+    defaultObjectReference = defaultTestObjectReference().build();
+    sor1 =
+        ObjectReferenceBuilder.newObjectReference()
+            .company("FirstCompany")
+            .value("FirstValue")
+            .type("FirstType")
+            .build();
+    sor2 =
+        ObjectReferenceBuilder.newObjectReference()
+            .company("SecondCompany")
+            .value("SecondValue")
+            .type("SecondType")
+            .build();
+  }
+
+  @WithAccessId(user = "admin")
+  @Test
+  void should_DeleteObjectReferences_When_DeletingTask() throws Exception {
+    Task createdTask =
+        createCompletedTask().objectReferences(sor1, sor2).buildAndStore(taskService);
+    taskService.deleteTask(createdTask.getId());
+    TaskanaEngineProxy engineProxy = new TaskanaEngineProxy(taskanaEngine);
+    ObjectReferenceMapper objectReferenceMapper =
+        engineProxy.getEngine().getSqlSession().getMapper(ObjectReferenceMapper.class);
+
+    try {
+      engineProxy.openConnection();
+      assertThat(objectReferenceMapper.findObjectReferencesByTaskId(createdTask.getId())).isEmpty();
+    } finally {
+      engineProxy.returnConnection();
+    }
+  }
+
+  @WithAccessId(user = "admin")
+  @Test
+  void should_DeleteObjectReferences_When_MultipleTasksAreDeleted() throws Exception {
+    Task firstCreatedTask = createCompletedTask().objectReferences(sor1).buildAndStore(taskService);
+    Task secondCreatedTask =
+        createCompletedTask().objectReferences(sor1, sor2).buildAndStore(taskService);
+    taskService.deleteTasks(List.of(firstCreatedTask.getId(), secondCreatedTask.getId()));
+    TaskanaEngineProxy engineProxy = new TaskanaEngineProxy(taskanaEngine);
+    ObjectReferenceMapper objectReferenceMapper =
+        engineProxy.getEngine().getSqlSession().getMapper(ObjectReferenceMapper.class);
+
+    try {
+      engineProxy.openConnection();
+      assertThat(
+              objectReferenceMapper.findObjectReferencesByTaskIds(
+                  List.of(firstCreatedTask.getId(), secondCreatedTask.getId())))
+          .isEmpty();
+    } finally {
+      engineProxy.returnConnection();
+    }
+  }
+
+  private TaskBuilder createCompletedTask() {
+    return (TaskBuilder.newTask()
+        .classificationSummary(defaultClassificationSummary)
+        .workbasketSummary(defaultWorkbasketSummary)
+        .primaryObjRef(defaultObjectReference)
+        .state(TaskState.COMPLETED));
+  }
+}

lib/taskana-core/src/test/java/acceptance/task/GetTaskWithSorAccTest.java

@@ -0,0 +1,91 @@
+package acceptance.task;
+
+import static acceptance.DefaultTestEntities.defaultTestClassification;
+import static acceptance.DefaultTestEntities.defaultTestObjectReference;
+import static acceptance.DefaultTestEntities.defaultTestWorkbasket;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import testapi.TaskanaInject;
+import testapi.TaskanaIntegrationTest;
+
+import pro.taskana.classification.api.ClassificationService;
+import pro.taskana.classification.api.models.ClassificationSummary;
+import pro.taskana.common.test.security.WithAccessId;
+import pro.taskana.task.api.TaskService;
+import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.builder.ObjectReferenceBuilder;
+import pro.taskana.task.internal.builder.TaskBuilder;
+import pro.taskana.workbasket.api.WorkbasketPermission;
+import pro.taskana.workbasket.api.WorkbasketService;
+import pro.taskana.workbasket.api.models.WorkbasketSummary;
+import pro.taskana.workbasket.internal.builder.WorkbasketAccessItemBuilder;
+
+@TaskanaIntegrationTest
+class GetTaskWithSorAccTest {
+
+  @TaskanaInject TaskService taskService;
+  @TaskanaInject WorkbasketService workbasketService;
+  @TaskanaInject ClassificationService classificationService;
+
+  ClassificationSummary defaultClassificationSummary;
+  WorkbasketSummary defaultWorkbasketSummary;
+  ObjectReference defaultObjectReference;
+
+  @WithAccessId(user = "businessadmin")
+  @BeforeAll
+  void setup() throws Exception {
+    defaultClassificationSummary =
+        defaultTestClassification().buildAndStoreAsSummary(classificationService);
+    defaultWorkbasketSummary = defaultTestWorkbasket().buildAndStoreAsSummary(workbasketService);
+
+    WorkbasketAccessItemBuilder.newWorkbasketAccessItem()
+        .workbasketId(defaultWorkbasketSummary.getId())
+        .accessId("user-1-1")
+        .permission(WorkbasketPermission.OPEN)
+        .permission(WorkbasketPermission.READ)
+        .permission(WorkbasketPermission.APPEND)
+        .buildAndStore(workbasketService);
+    defaultObjectReference = defaultTestObjectReference().build();
+  }
+
+  @WithAccessId(user = "user-1-1")
+  @Test
+  void should_ReturnTaskWithSor_When_RequestingTaskByTaskId() throws Exception {
+    Task task =
+        createDefaultTask()
+            .objectReferences(
+                defaultSecondaryObjectReference("0"), defaultSecondaryObjectReference("1"))
+            .buildAndStore(taskService);
+    Task result = taskService.getTask(task.getId());
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getType)
+        .containsExactly("Type0", "Type1");
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getValue)
+        .containsExactly("Value0", "Value1");
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getCompany)
+        .containsExactly("Company0", "Company1");
+  }
+
+  private TaskBuilder createDefaultTask() {
+    return (TaskBuilder.newTask()
+        .classificationSummary(defaultClassificationSummary)
+        .workbasketSummary(defaultWorkbasketSummary)
+        .primaryObjRef(defaultObjectReference));
+  }
+
+  private ObjectReference defaultSecondaryObjectReference(String suffix) {
+    return ObjectReferenceBuilder.newObjectReference()
+        .company("Company" + suffix)
+        .value("Value" + suffix)
+        .type("Type" + suffix)
+        .build();
+  }
+}

lib/taskana-core/src/test/java/acceptance/task/TaskModelsCloneTest.java

@@ -13,9 +13,9 @@ import org.junit.jupiter.api.Test;
 
 import pro.taskana.task.api.models.Attachment;
 import pro.taskana.task.api.models.AttachmentSummary;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.internal.models.AttachmentImpl;
 import pro.taskana.task.internal.models.AttachmentSummaryImpl;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.internal.models.TaskCommentImpl;
 import pro.taskana.task.internal.models.TaskImpl;
 import pro.taskana.task.internal.models.TaskSummaryImpl;
@@ -116,7 +116,7 @@ class TaskModelsCloneTest {
 
   @Test
   void should_CopyWithoutId_When_ObjectReferenceClone() {
-    ObjectReference dummyReference = new ObjectReference();
+    ObjectReferenceImpl dummyReference = new ObjectReferenceImpl();
     dummyReference.setId("dummyId");
     dummyReference.setSystem("dummySystem");
     dummyReference.setCompany("dummyCompany");
@@ -124,7 +124,7 @@ class TaskModelsCloneTest {
     dummyReference.setType("dummyType");
     dummyReference.setValue("dummyValue");
 
-    ObjectReference dummyReferenceCloned = dummyReference.copy();
+    ObjectReferenceImpl dummyReferenceCloned = dummyReference.copy();
 
     assertThat(dummyReferenceCloned).isNotEqualTo(dummyReference);
     dummyReferenceCloned.setId(dummyReference.getId());

lib/taskana-core/src/test/java/acceptance/task/TaskQueryImplAccTest.java

@@ -31,6 +31,7 @@ import pro.taskana.task.api.WildcardSearchField;
 import pro.taskana.task.api.models.Attachment;
 import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.TaskSummary;
+import pro.taskana.task.internal.builder.ObjectReferenceBuilder;
 import pro.taskana.task.internal.builder.TaskAttachmentBuilder;
 import pro.taskana.task.internal.builder.TaskBuilder;
 import pro.taskana.workbasket.api.WorkbasketPermission;
@@ -2429,6 +2430,532 @@ class TaskQueryImplAccTest {
       }
     }
 
+    @Nested
+    @TestInstance(Lifecycle.PER_CLASS)
+    class QueryingObjectReferenceCombinations {
+      WorkbasketSummary wb;
+      TaskSummary taskSummary1;
+      TaskSummary taskSummary2;
+      TaskSummary taskSummary3;
+      TaskSummary taskSummary4;
+      TaskSummary taskSummary5;
+      TaskSummary taskSummary6;
+      TaskSummary taskSummary7;
+
+      @WithAccessId(user = "user-1-1")
+      @BeforeAll
+      void setup() throws Exception {
+        wb = createWorkbasketWithPermission();
+        ObjectReference sor1 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("FirstValue")
+                .type("FirstType")
+                .build();
+        taskSummary1 =
+            taskInWorkbasket(wb).objectReferences(sor1).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor2 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("SecondValue")
+                .type("SecondType")
+                .build();
+        taskSummary2 =
+            taskInWorkbasket(wb).objectReferences(sor2).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor2copy = sor2.copy();
+        ObjectReference sor1copy = sor1.copy();
+        taskSummary3 =
+            taskInWorkbasket(wb)
+                .objectReferences(sor2copy, sor1copy)
+                .buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor3 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("SecondCompany")
+                .value("SecondValue")
+                .type("SecondType")
+                .build();
+        taskSummary4 =
+            taskInWorkbasket(wb).objectReferences(sor1, sor3).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor4 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("SecondCompany")
+                .value("ThirdValue")
+                .type("ThirdType")
+                .build();
+        taskSummary5 =
+            taskInWorkbasket(wb).objectReferences(sor4).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor5 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("ThirdValue")
+                .type("FirstType")
+                .build();
+        taskSummary6 =
+            taskInWorkbasket(wb).objectReferences(sor5).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor6 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("FirstValue")
+                .type("ThirdType")
+                .build();
+        taskSummary7 =
+            taskInWorkbasket(wb).objectReferences(sor6).buildAndStoreAsSummary(taskService);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForValueInCompanyIn() {
+        List<TaskSummary> tasks =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorValueIn("SecondValue")
+                .sorCompanyIn("FirstCompany")
+                .list();
+
+        assertThat(tasks).hasSize(2);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForValueInMultipleCompanyIn() {
+        List<TaskSummary> tasks =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorValueIn("SecondValue")
+                .sorCompanyIn("FirstCompany", "SecondCompany")
+                .list();
+
+        assertThat(tasks).hasSize(3);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForValueInMultipleTypeLikeMultiple() {
+        List<TaskSummary> tasks =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorValueIn("FirstValue", "ThirdValue")
+                .sorTypeLike("First%", "Third%")
+                .list();
+
+        assertThat(tasks).hasSize(5);
+      }
+    }
+
+    @Nested
+    @TestInstance(Lifecycle.PER_CLASS)
+    class ObjectReferenceValue {
+      WorkbasketSummary wb;
+      TaskSummary taskSummary1;
+      TaskSummary taskSummary2;
+      TaskSummary taskSummary3;
+
+      @WithAccessId(user = "user-1-1")
+      @BeforeAll
+      void setup() throws Exception {
+        wb = createWorkbasketWithPermission();
+        ObjectReference sor1 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("FirstValue")
+                .type("FirstType")
+                .build();
+        ObjectReference sor2 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("SecondValue")
+                .type("SecondType")
+                .build();
+
+        ObjectReference sor2copy = sor2.copy();
+        ObjectReference sor1copy = sor1.copy();
+
+        taskSummary1 =
+            taskInWorkbasket(wb).objectReferences(sor1).buildAndStoreAsSummary(taskService);
+        taskSummary2 =
+            taskInWorkbasket(wb).objectReferences(sor2).buildAndStoreAsSummary(taskService);
+        taskSummary3 =
+            taskInWorkbasket(wb)
+                .objectReferences(sor2copy, sor1copy)
+                .buildAndStoreAsSummary(taskService);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForValueIn() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorValueIn("FirstValue")
+                .list();
+
+        assertThat(list).containsExactlyInAnyOrder(taskSummary1, taskSummary3);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_CountCorrectly_When_QueryingForValueIn() {
+        long numberOfTasks =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorValueIn("FirstValue")
+                .count();
+
+        assertThat(numberOfTasks).isEqualTo(2);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForValueLike() {
+        List<TaskSummary> list =
+            taskService.createTaskQuery().workbasketIdIn(wb.getId()).sorValueLike("%Value").list();
+        assertThat(list).containsExactlyInAnyOrder(taskSummary1, taskSummary2, taskSummary3);
+      }
+    }
+
+    @Nested
+    @TestInstance(Lifecycle.PER_CLASS)
+    class ObjectReferenceType {
+      WorkbasketSummary wb;
+      TaskSummary taskSummary1;
+      TaskSummary taskSummary2;
+      TaskSummary taskSummary3;
+      TaskSummary taskSummary4;
+
+      @WithAccessId(user = "user-1-1")
+      @BeforeAll
+      void setup() throws Exception {
+        wb = createWorkbasketWithPermission();
+        ObjectReference sor1 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("FirstValue")
+                .type("FirstType")
+                .build();
+        taskSummary1 =
+            taskInWorkbasket(wb).objectReferences(sor1).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor2 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("FirstValue")
+                .type("SecondType")
+                .build();
+        taskSummary2 =
+            taskInWorkbasket(wb).objectReferences(sor2).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor2copy = sor2.copy();
+        ObjectReference sor1copy = sor1.copy();
+        taskSummary3 =
+            taskInWorkbasket(wb)
+                .objectReferences(sor2copy, sor1copy)
+                .buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor3 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("FirstValue")
+                .type("ThirdType")
+                .build();
+        taskSummary4 =
+            taskInWorkbasket(wb).objectReferences(sor3).buildAndStoreAsSummary(taskService);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForTypeIn() {
+        List<TaskSummary> list =
+            taskService.createTaskQuery().workbasketIdIn(wb.getId()).sorTypeIn("FirstType").list();
+
+        assertThat(list).containsExactlyInAnyOrder(taskSummary1, taskSummary3);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ReturnSingleTaskSummary_When_QueryingForTypeLikeUsingSingle() {
+        TaskSummary result =
+            taskService.createTaskQuery().workbasketIdIn(wb.getId()).sorTypeLike("Third%").single();
+        assertThat(result).isEqualTo(taskSummary4);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ReturnEmptyList_When_QueryingForNonexistentTypeLike() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorTypeLike("%NoSuchType")
+                .list();
+        assertThat(list).isEmpty();
+      }
+    }
+
+    @Nested
+    @TestInstance(Lifecycle.PER_CLASS)
+    class ObjectReferenceCompany {
+      WorkbasketSummary wb;
+      TaskSummary taskSummary1;
+      TaskSummary taskSummary2;
+      TaskSummary taskSummary3;
+
+      @WithAccessId(user = "user-1-1")
+      @BeforeAll
+      void setup() throws Exception {
+        wb = createWorkbasketWithPermission();
+        ObjectReference sor1 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("FirstValue")
+                .type("FirstType")
+                .build();
+        ObjectReference sor2 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("SecondCompany")
+                .value("FirstValue")
+                .type("SecondType")
+                .build();
+        ObjectReference sor2copy = sor2.copy();
+        ObjectReference sor1copy = sor1.copy();
+
+        taskSummary1 =
+            taskInWorkbasket(wb).objectReferences(sor1).buildAndStoreAsSummary(taskService);
+        taskSummary2 =
+            taskInWorkbasket(wb).objectReferences(sor2).buildAndStoreAsSummary(taskService);
+        taskSummary3 =
+            taskInWorkbasket(wb)
+                .objectReferences(sor2copy, sor1copy)
+                .buildAndStoreAsSummary(taskService);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForCompanyInWithLimit() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorCompanyIn("FirstCompany")
+                .list(0, 1);
+        assertThat(list).hasSize(1).containsAnyOf(taskSummary1, taskSummary3);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForCompanyLike() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorCompanyLike("%Company")
+                .list();
+        assertThat(list).containsExactlyInAnyOrder(taskSummary1, taskSummary2, taskSummary3);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ReturnEmptyList_When_QueryingForNonexistentCompanyLike() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorCompanyLike("%NoSuchCompany")
+                .list();
+        assertThat(list).isEmpty();
+      }
+    }
+
+    @Nested
+    @TestInstance(Lifecycle.PER_CLASS)
+    class ObjectReferenceSystem {
+      WorkbasketSummary wb;
+      TaskSummary taskSummary1;
+      TaskSummary taskSummary2;
+      TaskSummary taskSummary3;
+      TaskSummary taskSummary4;
+
+      @WithAccessId(user = "user-1-1")
+      @BeforeAll
+      void setup() throws Exception {
+        wb = createWorkbasketWithPermission();
+        ObjectReference sor1 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("FirstValue")
+                .type("FirstType")
+                .system("FirstSystem")
+                .build();
+        taskSummary1 =
+            taskInWorkbasket(wb).objectReferences(sor1).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor2 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("SecondCompany")
+                .value("FirstValue")
+                .type("SecondType")
+                .system("SecondSystem")
+                .build();
+        taskSummary2 =
+            taskInWorkbasket(wb).objectReferences(sor2).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor2copy = sor2.copy();
+        ObjectReference sor1copy = sor1.copy();
+        taskSummary3 =
+            taskInWorkbasket(wb)
+                .objectReferences(sor2copy, sor1copy)
+                .buildAndStoreAsSummary(taskService);
+
+        ObjectReference objRefNoSystem =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("SecondCompany")
+                .value("FirstValue")
+                .type("SecondType")
+                .build();
+        taskSummary4 =
+            taskInWorkbasket(wb)
+                .objectReferences(objRefNoSystem)
+                .buildAndStoreAsSummary(taskService);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForSystemIn() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorSystemIn("FirstSystem")
+                .list();
+
+        assertThat(list).containsExactlyInAnyOrder(taskSummary1, taskSummary3);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForSystemLike() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorSystemLike("%System")
+                .list();
+        assertThat(list).containsExactlyInAnyOrder(taskSummary1, taskSummary2, taskSummary3);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ReturnEmptyList_When_QueryingForNonexistentSystemLike() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorSystemLike("%NoSuchSystem")
+                .list();
+        assertThat(list).isEmpty();
+      }
+    }
+
+    @Nested
+    @TestInstance(Lifecycle.PER_CLASS)
+    class ObjectReferenceSystemInstance {
+      WorkbasketSummary wb;
+      TaskSummary taskSummary1;
+      TaskSummary taskSummary2;
+      TaskSummary taskSummary3;
+      TaskSummary taskSummary4;
+
+      @WithAccessId(user = "user-1-1")
+      @BeforeAll
+      void setup() throws Exception {
+        wb = createWorkbasketWithPermission();
+        ObjectReference sor1 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("FirstCompany")
+                .value("FirstValue")
+                .type("FirstType")
+                .systemInstance("FirstSystemInstance")
+                .build();
+        taskSummary1 =
+            taskInWorkbasket(wb).objectReferences(sor1).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor2 =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("SecondCompany")
+                .value("FirstValue")
+                .type("SecondType")
+                .systemInstance("SecondSystemInstance")
+                .build();
+        taskSummary2 =
+            taskInWorkbasket(wb).objectReferences(sor2).buildAndStoreAsSummary(taskService);
+
+        ObjectReference sor2copy = sor2.copy();
+        ObjectReference sor1copy = sor1.copy();
+        taskSummary3 =
+            taskInWorkbasket(wb)
+                .objectReferences(sor2copy, sor1copy)
+                .buildAndStoreAsSummary(taskService);
+
+        ObjectReference objRefNoSystem =
+            ObjectReferenceBuilder.newObjectReference()
+                .company("SecondCompany")
+                .value("FirstValue")
+                .type("SecondType")
+                .build();
+        taskSummary4 =
+            taskInWorkbasket(wb)
+                .objectReferences(objRefNoSystem)
+                .buildAndStoreAsSummary(taskService);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForSystemInstanceIn() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorSystemInstanceIn("FirstSystemInstance")
+                .list();
+
+        assertThat(list).containsExactlyInAnyOrder(taskSummary1, taskSummary3);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ApplyFilter_When_QueryingForSystemInstanceLike() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorSystemInstanceLike("%SystemInstance")
+                .list();
+        assertThat(list).containsExactlyInAnyOrder(taskSummary1, taskSummary2, taskSummary3);
+      }
+
+      @WithAccessId(user = "user-1-1")
+      @Test
+      void should_ReturnEmptyList_When_QueryingForNonexistentSystemInstanceLike() {
+        List<TaskSummary> list =
+            taskService
+                .createTaskQuery()
+                .workbasketIdIn(wb.getId())
+                .sorSystemInstanceLike("%NoSuchSystemInstance")
+                .list();
+        assertThat(list).isEmpty();
+      }
+    }
+
     @Nested
     @TestInstance(Lifecycle.PER_CLASS)
     class CustomAttributes {}

lib/taskana-core/src/test/java/acceptance/task/UpdateTaskAccTest.java

@@ -31,9 +31,9 @@ import pro.taskana.common.test.security.WithAccessId;
 import pro.taskana.task.api.TaskCustomField;
 import pro.taskana.task.api.TaskState;
 import pro.taskana.task.api.exceptions.TaskNotFoundException;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
 import pro.taskana.task.api.models.TaskSummary;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.internal.models.TaskImpl;
 
 /** Acceptance test for all "update task" scenarios. */
@@ -258,7 +258,7 @@ class UpdateTaskAccTest extends AbstractAccTest {
   @Test
   void should_UpdateNoTasks_When_UpdateTasksWithUnmatchedObjectReferenceWasCalled()
       throws Exception {
-    ObjectReference por = new ObjectReference();
+    ObjectReferenceImpl por = new ObjectReferenceImpl();
     por.setCompany("00");
     por.setSystem("PASystem");
     por.setSystemInstance("00");
@@ -277,7 +277,7 @@ class UpdateTaskAccTest extends AbstractAccTest {
   @WithAccessId(user = "teamlead-1")
   @Test
   void should_UpdateTasks_When_MatchingPrimaryObjectReferenceWasChanged() throws Exception {
-    ObjectReference por = new ObjectReference();
+    ObjectReferenceImpl por = new ObjectReferenceImpl();
     por.setCompany("00");
     por.setSystem("PASystem");
     por.setSystemInstance("00");

lib/taskana-core/src/test/java/acceptance/task/UpdateTaskWithSorAccTest.java

@@ -0,0 +1,169 @@
+package acceptance.task;
+
+import static acceptance.DefaultTestEntities.defaultTestClassification;
+import static acceptance.DefaultTestEntities.defaultTestObjectReference;
+import static acceptance.DefaultTestEntities.defaultTestWorkbasket;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import testapi.TaskanaInject;
+import testapi.TaskanaIntegrationTest;
+
+import pro.taskana.classification.api.ClassificationService;
+import pro.taskana.classification.api.models.ClassificationSummary;
+import pro.taskana.common.test.security.WithAccessId;
+import pro.taskana.task.api.TaskService;
+import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.builder.ObjectReferenceBuilder;
+import pro.taskana.task.internal.builder.TaskBuilder;
+import pro.taskana.workbasket.api.WorkbasketPermission;
+import pro.taskana.workbasket.api.WorkbasketService;
+import pro.taskana.workbasket.api.models.WorkbasketSummary;
+import pro.taskana.workbasket.internal.builder.WorkbasketAccessItemBuilder;
+
+/** Acceptance test for "update task" scenarios that involve secondary {@link ObjectReference}s. */
+@TaskanaIntegrationTest
+class UpdateTaskWithSorAccTest {
+
+  @TaskanaInject TaskService taskService;
+  @TaskanaInject WorkbasketService workbasketService;
+  @TaskanaInject ClassificationService classificationService;
+
+  ClassificationSummary defaultClassificationSummary;
+  WorkbasketSummary defaultWorkbasketSummary;
+  ObjectReference defaultObjectReference;
+
+  @WithAccessId(user = "businessadmin")
+  @BeforeAll
+  void setup() throws Exception {
+    defaultClassificationSummary =
+        defaultTestClassification().buildAndStoreAsSummary(classificationService);
+    defaultWorkbasketSummary = defaultTestWorkbasket().buildAndStoreAsSummary(workbasketService);
+
+    WorkbasketAccessItemBuilder.newWorkbasketAccessItem()
+        .workbasketId(defaultWorkbasketSummary.getId())
+        .accessId("user-1-1")
+        .permission(WorkbasketPermission.OPEN)
+        .permission(WorkbasketPermission.READ)
+        .permission(WorkbasketPermission.APPEND)
+        .buildAndStore(workbasketService);
+    defaultObjectReference = defaultTestObjectReference().build();
+  }
+
+  @WithAccessId(user = "user-1-1")
+  @Test
+  void should_NotChangeSor_When_UpdateWithoutChanges() throws Exception {
+    Task task =
+        createDefaultTask()
+            .objectReferences(
+                defaultSecondaryObjectReference("0"), defaultSecondaryObjectReference("1"))
+            .buildAndStore(taskService);
+    taskService.updateTask(task);
+    Task result = taskService.getTask(task.getId());
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getType)
+        .containsExactlyInAnyOrder("Type0", "Type1");
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getValue)
+        .containsExactlyInAnyOrder("Value0", "Value1");
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getCompany)
+        .containsExactlyInAnyOrder("Company0", "Company1");
+  }
+
+  @WithAccessId(user = "user-1-1")
+  @Test
+  void should_UpdateExistingSor_When_SorChangedInUpdatedTask() throws Exception {
+    Task task =
+        createDefaultTask()
+            .objectReferences(
+                defaultSecondaryObjectReference("0"), defaultSecondaryObjectReference("1"))
+            .buildAndStore(taskService);
+
+    ObjectReference sorToUpdate = task.getSecondaryObjectReferences().get(0);
+    sorToUpdate.setType("NewType");
+
+    taskService.updateTask(task);
+    Task result = taskService.getTask(task.getId());
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getType)
+        .containsExactlyInAnyOrder("NewType", "Type1");
+  }
+
+  @WithAccessId(user = "user-1-1")
+  @Test
+  void should_AddNewSor_When_UpdatedTaskContainsNewSor() throws Exception {
+    Task task =
+        createDefaultTask()
+            .objectReferences(
+                defaultSecondaryObjectReference("0"), defaultSecondaryObjectReference("1"))
+            .buildAndStore(taskService);
+    task.addSecondaryObjectReference("NewCompany", null, null, "NewType", "NewValue");
+    taskService.updateTask(task);
+    Task result = taskService.getTask(task.getId());
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getType)
+        .containsExactlyInAnyOrder("Type0", "Type1", "NewType");
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getValue)
+        .containsExactlyInAnyOrder("Value0", "Value1", "NewValue");
+
+    assertThat(result.getSecondaryObjectReferences())
+        .extracting(ObjectReference::getCompany)
+        .containsExactlyInAnyOrder("Company0", "Company1", "NewCompany");
+  }
+
+  @WithAccessId(user = "user-1-1")
+  @Test
+  void should_DeleteOneSor_When_UpdatedTaskContainsOneLessSor() throws Exception {
+    Task task =
+        createDefaultTask()
+            .objectReferences(
+                defaultSecondaryObjectReference("0"), defaultSecondaryObjectReference("1"))
+            .buildAndStore(taskService);
+    task.removeSecondaryObjectReference(task.getSecondaryObjectReferences().get(0).getId());
+    taskService.updateTask(task);
+    Task result = taskService.getTask(task.getId());
+
+    assertThat(result.getSecondaryObjectReferences()).hasSize(1);
+  }
+
+  @WithAccessId(user = "user-1-1")
+  @Test
+  void should_DeleteAllSor_When_UpdatedTaskContainsNoSor() throws Exception {
+    Task task =
+        createDefaultTask()
+            .objectReferences(
+                defaultSecondaryObjectReference("0"), defaultSecondaryObjectReference("1"))
+            .buildAndStore(taskService);
+    task.removeSecondaryObjectReference(task.getSecondaryObjectReferences().get(0).getId());
+    task.removeSecondaryObjectReference(task.getSecondaryObjectReferences().get(0).getId());
+    taskService.updateTask(task);
+    Task result = taskService.getTask(task.getId());
+
+    assertThat(result.getSecondaryObjectReferences()).isEmpty();
+  }
+
+  private TaskBuilder createDefaultTask() {
+    return (TaskBuilder.newTask()
+        .classificationSummary(defaultClassificationSummary)
+        .workbasketSummary(defaultWorkbasketSummary)
+        .primaryObjRef(defaultObjectReference));
+  }
+
+  private ObjectReference defaultSecondaryObjectReference(String suffix) {
+    return ObjectReferenceBuilder.newObjectReference()
+        .company("Company" + suffix)
+        .value("Value" + suffix)
+        .type("Type" + suffix)
+        .build();
+  }
+}

lib/taskana-spring-example/src/main/java/pro/taskana/example/ExampleBootstrap.java

@@ -17,10 +17,11 @@ import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.exceptions.AttachmentPersistenceException;
 import pro.taskana.task.api.exceptions.InvalidOwnerException;
 import pro.taskana.task.api.exceptions.InvalidStateException;
+import pro.taskana.task.api.exceptions.ObjectReferencePersistenceException;
 import pro.taskana.task.api.exceptions.TaskAlreadyExistException;
 import pro.taskana.task.api.exceptions.TaskNotFoundException;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.workbasket.api.WorkbasketType;
 import pro.taskana.workbasket.api.exceptions.WorkbasketAlreadyExistException;
 import pro.taskana.workbasket.api.exceptions.WorkbasketNotFoundException;
@@ -41,7 +42,7 @@ public class ExampleBootstrap {
           NotAuthorizedException, ClassificationAlreadyExistException,
           MalformedServiceLevelException, TaskAlreadyExistException, WorkbasketNotFoundException,
           ClassificationNotFoundException, AttachmentPersistenceException, TaskNotFoundException,
-          InvalidOwnerException, InvalidStateException {
+          InvalidOwnerException, InvalidStateException, ObjectReferencePersistenceException {
     System.out.println("---------------------------> Start App");
 
     Workbasket wb = taskanaEngine.getWorkbasketService().newWorkbasket("workbasket", "DOMAIN_A");
@@ -56,7 +57,7 @@ public class ExampleBootstrap {
     Task task = taskanaEngine.getTaskService().newTask(wb.getId());
     task.setName("Spring example task");
     task.setClassificationKey(classification.getKey());
-    ObjectReference objRef = new ObjectReference();
+    ObjectReferenceImpl objRef = new ObjectReferenceImpl();
     objRef.setCompany("aCompany");
     objRef.setSystem("aSystem");
     objRef.setSystemInstance("anInstance");

lib/taskana-spring-example/src/test/java/pro/taskana/example/TaskanaTransactionIntTest.java

@@ -31,6 +31,7 @@ import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
 import pro.taskana.task.api.models.TaskSummary;
 import pro.taskana.task.internal.jobs.TaskCleanupJob;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.internal.models.TaskImpl;
 import pro.taskana.workbasket.api.WorkbasketService;
 import pro.taskana.workbasket.api.WorkbasketType;
@@ -230,7 +231,7 @@ class TaskanaTransactionIntTest {
   }
 
   private static ObjectReference createDefaultObjRef() {
-    ObjectReference objRef = new ObjectReference();
+    ObjectReferenceImpl objRef = new ObjectReferenceImpl();
     objRef.setCompany("company");
     objRef.setSystem("system");
     objRef.setSystemInstance("instance");

lib/taskana-spring/src/test/java/pro/taskana/common/internal/transaction/TaskanaComponent.java

@@ -9,9 +9,10 @@ import pro.taskana.common.api.exceptions.InvalidArgumentException;
 import pro.taskana.common.api.exceptions.NotAuthorizedException;
 import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.exceptions.AttachmentPersistenceException;
+import pro.taskana.task.api.exceptions.ObjectReferencePersistenceException;
 import pro.taskana.task.api.exceptions.TaskAlreadyExistException;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.workbasket.api.exceptions.WorkbasketNotFoundException;
 
 /** TODO. */
@@ -27,10 +28,11 @@ public class TaskanaComponent {
 
   public void triggerRollback()
       throws NotAuthorizedException, WorkbasketNotFoundException, ClassificationNotFoundException,
-          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException {
+          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException,
+          ObjectReferencePersistenceException {
     Task task = taskService.newTask("1");
     task.setName("Unit Test Task");
-    ObjectReference objRef = new ObjectReference();
+    ObjectReferenceImpl objRef = new ObjectReferenceImpl();
     objRef.setCompany("aCompany");
     objRef.setSystem("aSystem");
     objRef.setSystemInstance("anInstance");

rest/taskana-rest-spring/src/main/java/pro/taskana/common/rest/JsonPropertyEditorRegistrator.java

@@ -8,6 +8,7 @@ import org.springframework.web.bind.annotation.InitBinder;
 
 import pro.taskana.monitor.rest.models.PriorityColumnHeaderRepresentationModel;
 import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 
 @ControllerAdvice
 public class JsonPropertyEditorRegistrator {
@@ -25,6 +26,6 @@ public class JsonPropertyEditorRegistrator {
         PriorityColumnHeaderRepresentationModel.class,
         new JsonPropertyEditor(objectMapper, PriorityColumnHeaderRepresentationModel.class));
     binder.registerCustomEditor(
-        ObjectReference.class, new JsonPropertyEditor(objectMapper, ObjectReference.class));
+        ObjectReference.class, new JsonPropertyEditor(objectMapper, ObjectReferenceImpl.class));
   }
 }

rest/taskana-rest-spring/src/main/java/pro/taskana/task/rest/TaskController.java

@@ -37,6 +37,7 @@ import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.exceptions.AttachmentPersistenceException;
 import pro.taskana.task.api.exceptions.InvalidOwnerException;
 import pro.taskana.task.api.exceptions.InvalidStateException;
+import pro.taskana.task.api.exceptions.ObjectReferencePersistenceException;
 import pro.taskana.task.api.exceptions.TaskAlreadyExistException;
 import pro.taskana.task.api.exceptions.TaskNotFoundException;
 import pro.taskana.task.api.models.Task;
@@ -84,13 +85,11 @@ public class TaskController {
       TaskQueryFilterParameter filterParameter,
       TaskQuerySortParameter sortParameter,
       QueryPagingParameter<TaskSummary, TaskQuery> pagingParameter) {
-
     QueryParamsValidator.validateParams(
         request,
         TaskQueryFilterParameter.class,
         QuerySortParameter.class,
         QueryPagingParameter.class);
-
     TaskQuery query = taskService.createTaskQuery();
 
     filterParameter.apply(query);
@@ -332,6 +331,8 @@ public class TaskController {
    * @throws InvalidArgumentException if any input is semantically wrong.
    * @throws AttachmentPersistenceException if an Attachment with ID will be added multiple times
    *     without using the task-methods
+   * @throws ObjectReferencePersistenceException if an ObjectReference with ID will be added
+   *     multiple times without using the task-methods
    * @title Create a new Task
    */
   @PostMapping(path = RestEndpoints.URL_TASKS)
@@ -339,7 +340,8 @@ public class TaskController {
   public ResponseEntity<TaskRepresentationModel> createTask(
       @RequestBody TaskRepresentationModel taskRepresentationModel)
       throws WorkbasketNotFoundException, ClassificationNotFoundException, NotAuthorizedException,
-          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException {
+          TaskAlreadyExistException, InvalidArgumentException, AttachmentPersistenceException,
+          ObjectReferencePersistenceException {
     Task fromResource = taskRepresentationModelAssembler.toEntityModel(taskRepresentationModel);
     Task createdTask = taskService.createTask(fromResource);
 
@@ -388,6 +390,8 @@ public class TaskController {
    * @throws NotAuthorizedException if the current user is not authorized.
    * @throws AttachmentPersistenceException if the modified Task contains two attachments with the
    *     same id.
+   * @throws ObjectReferencePersistenceException if the modified Task contains two object references
+   *     with the same id.
    * @throws InvalidStateException if an attempt is made to change the owner of the Task and the
    *     Task is not in state READY.
    * @title Update a Task
@@ -399,7 +403,7 @@ public class TaskController {
       @RequestBody TaskRepresentationModel taskRepresentationModel)
       throws TaskNotFoundException, ClassificationNotFoundException, InvalidArgumentException,
           ConcurrencyException, NotAuthorizedException, AttachmentPersistenceException,
-          InvalidStateException {
+          InvalidStateException, ObjectReferencePersistenceException {
     if (!taskId.equals(taskRepresentationModel.getTaskId())) {
       throw new InvalidArgumentException(
           String.format(

rest/taskana-rest-spring/src/main/java/pro/taskana/task/rest/TaskQueryFilterParameter.java

@@ -859,6 +859,91 @@ public class TaskQueryFilterParameter implements QueryParameter<TaskQuery, Void>
    */
   @JsonProperty("por-value-not-like")
   private final String[] porValueNotLike;
+  // endregion
+  // region secondaryObjectReference
+  /**
+   * Filter by the primary object reference of the task. This is an exact match. "sor" is a
+   * parameter of complex type. Its following attributes from sor[].id to sor[].value can be
+   * specified according to the description of complex parameters in the overview, e.g.
+   * sor={"value":"exampleValue"}
+   */
+  @JsonProperty("sor")
+  private final ObjectReference[] secondaryObjectReferenceIn;
+  // endregion
+  // region secondaryObjectReferenceCompany
+  /**
+   * Filter by the company of the secondary object reference of the task. This is an exact match.
+   */
+  @JsonProperty("sor-company")
+  private final String[] sorCompanyIn;
+
+  /**
+   * Filter by the company of the secondary object references of the task. This results in a
+   * substring search (% is appended to the front and end of the requested value). Further SQL
+   * "LIKE" wildcard characters will be resolved correctly.
+   */
+  @JsonProperty("sor-company-like")
+  private final String[] sorCompanyLike;
+
+  // endregion
+  // region secondaryObjectReferenceSystem
+  /** Filter by the system of the secondary object reference of the task. This is an exact match. */
+  @JsonProperty("sor-system")
+  private final String[] sorSystemIn;
+
+  /**
+   * Filter by the system of the secondary object reference of the task. This results in a substring
+   * search (% is appended to the front and end of the requested value). Further SQL "LIKE" wildcard
+   * characters will be resolved correctly.
+   */
+  @JsonProperty("sor-system-like")
+  private final String[] sorSystemLike;
+
+  // endregion
+  // region secondaryObjectReferenceSystemInstance
+  /**
+   * Filter by the system instance of the secondary object reference of the task. This is an exact
+   * match.
+   */
+  @JsonProperty("sor-instance")
+  private final String[] sorInstanceIn;
+
+  /**
+   * Filter by the system instance of the secondary object reference of the task. This results in a
+   * substring search (% is appended to the front and end of the requested value). Further SQL
+   * "LIKE" wildcard characters will be resolved correctly.
+   */
+  @JsonProperty("sor-instance-like")
+  private final String[] sorInstanceLike;
+
+  // endregion
+  // region secondaryObjectReferenceSystemType
+  /** Filter by the type of the secondary object reference of the task. This is an exact match. */
+  @JsonProperty("sor-type")
+  private final String[] sorTypeIn;
+
+  /**
+   * Filter by the type of the secondary object reference of the task. This results in a substring
+   * search (% is appended to the front and end of the requested value). Further SQL "LIKE" wildcard
+   * characters will be resolved correctly.
+   */
+  @JsonProperty("sor-type-like")
+  private final String[] sorTypeLike;
+
+  // endregion
+  // region primaryObjectReferenceSystemValue
+  /** Filter by the value of the secondary object reference of the task. This is an exact match. */
+  @JsonProperty("sor-value")
+  private final String[] sorValueIn;
+
+  /**
+   * Filter by the value of the secondary object reference of the task. This results in a substring
+   * search (% is appended to the front and end of the requested value). Further SQL "LIKE" wildcard
+   * characters will be resolved correctly.
+   */
+  @JsonProperty("sor-value-like")
+  private final String[] sorValueLike;
+
   // endregion
   // region read
   /** Filter by the is read flag of the task. This is an exact match. */
@@ -1527,6 +1612,17 @@ public class TaskQueryFilterParameter implements QueryParameter<TaskQuery, Void>
     "por-value-not",
     "por-value-like",
     "por-value-not-like",
+    "sor",
+    "sor-company",
+    "sor-company-like",
+    "sor-system",
+    "sor-system-like",
+    "sor-instance",
+    "sor-instance-like",
+    "sor-type",
+    "sor-type-like",
+    "sor-value",
+    "sor-value-like",
     "is-read",
     "is-transferred",
     "attachment-classification-id",
@@ -1725,6 +1821,17 @@ public class TaskQueryFilterParameter implements QueryParameter<TaskQuery, Void>
       String[] porValueNotIn,
       String[] porValueLike,
       String[] porValueNotLike,
+      ObjectReference[] secondaryObjectReferenceIn,
+      String[] sorCompanyIn,
+      String[] sorCompanyLike,
+      String[] sorSystemIn,
+      String[] sorSystemLike,
+      String[] sorInstanceIn,
+      String[] sorInstanceLike,
+      String[] sorTypeIn,
+      String[] sorTypeLike,
+      String[] sorValueIn,
+      String[] sorValueLike,
       Boolean isRead,
       Boolean isTransferred,
       String[] attachmentClassificationIdIn,
@@ -1922,6 +2029,17 @@ public class TaskQueryFilterParameter implements QueryParameter<TaskQuery, Void>
     this.porValueNotIn = porValueNotIn;
     this.porValueLike = porValueLike;
     this.porValueNotLike = porValueNotLike;
+    this.secondaryObjectReferenceIn = secondaryObjectReferenceIn;
+    this.sorCompanyIn = sorCompanyIn;
+    this.sorCompanyLike = sorCompanyLike;
+    this.sorSystemIn = sorSystemIn;
+    this.sorSystemLike = sorSystemLike;
+    this.sorInstanceIn = sorInstanceIn;
+    this.sorInstanceLike = sorInstanceLike;
+    this.sorTypeIn = sorTypeIn;
+    this.sorTypeLike = sorTypeLike;
+    this.sorValueIn = sorValueIn;
+    this.sorValueLike = sorValueLike;
     this.isRead = isRead;
     this.isTransferred = isTransferred;
     this.attachmentClassificationIdIn = attachmentClassificationIdIn;
@@ -2261,6 +2379,31 @@ public class TaskQueryFilterParameter implements QueryParameter<TaskQuery, Void>
         .map(this::wrapElementsInLikeStatement)
         .ifPresent(query::primaryObjectReferenceValueNotLike);
 
+    Optional.ofNullable(secondaryObjectReferenceIn).ifPresent(query::secondaryObjectReferenceIn);
+
+    Optional.ofNullable(sorCompanyIn).ifPresent(query::sorCompanyIn);
+    Optional.ofNullable(sorCompanyLike)
+        .map(this::wrapElementsInLikeStatement)
+        .ifPresent(query::sorCompanyLike);
+
+    Optional.ofNullable(sorSystemIn).ifPresent(query::sorSystemIn);
+    Optional.ofNullable(sorSystemLike)
+        .map(this::wrapElementsInLikeStatement)
+        .ifPresent(query::sorSystemLike);
+
+    Optional.ofNullable(sorInstanceIn).ifPresent(query::sorSystemInstanceIn);
+    Optional.ofNullable(sorInstanceLike)
+        .map(this::wrapElementsInLikeStatement)
+        .ifPresent(query::sorSystemInstanceLike);
+    Optional.ofNullable(sorTypeIn).ifPresent(query::sorTypeIn);
+    Optional.ofNullable(sorTypeLike)
+        .map(this::wrapElementsInLikeStatement)
+        .ifPresent(query::sorTypeLike);
+    Optional.ofNullable(sorValueIn).ifPresent(query::sorValueIn);
+    Optional.ofNullable(sorValueLike)
+        .map(this::wrapElementsInLikeStatement)
+        .ifPresent(query::sorValueLike);
+
     Optional.ofNullable(isRead).ifPresent(query::readEquals);
 
     Optional.ofNullable(isTransferred).ifPresent(query::transferredEquals);

rest/taskana-rest-spring/src/main/java/pro/taskana/task/rest/assembler/ObjectReferenceRepresentationModelAssembler.java

@@ -5,6 +5,7 @@ import org.springframework.lang.NonNull;
 import org.springframework.stereotype.Controller;
 
 import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.rest.models.ObjectReferenceRepresentationModel;
 
 @Controller
@@ -16,6 +17,7 @@ public class ObjectReferenceRepresentationModelAssembler
   public ObjectReferenceRepresentationModel toModel(@NonNull ObjectReference entity) {
     ObjectReferenceRepresentationModel repModel = new ObjectReferenceRepresentationModel();
     repModel.setId(entity.getId());
+    repModel.setTaskId(entity.getTaskId());
     repModel.setCompany(entity.getCompany());
     repModel.setSystem(entity.getSystem());
     repModel.setSystemInstance(entity.getSystemInstance());
@@ -25,8 +27,9 @@ public class ObjectReferenceRepresentationModelAssembler
   }
 
   public ObjectReference toEntity(ObjectReferenceRepresentationModel repModel) {
-    ObjectReference objectReference = new ObjectReference();
+    ObjectReferenceImpl objectReference = new ObjectReferenceImpl();
     objectReference.setId(repModel.getId());
+    objectReference.setTaskId(repModel.getTaskId());
     objectReference.setCompany(repModel.getCompany());
     objectReference.setSystem(repModel.getSystem());
     objectReference.setSystemInstance(repModel.getSystemInstance());

rest/taskana-rest-spring/src/main/java/pro/taskana/task/rest/assembler/TaskRepresentationModelAssembler.java

@@ -74,6 +74,10 @@ public class TaskRepresentationModelAssembler
     repModel.setOwner(task.getOwner());
     repModel.setOwnerLongName(task.getOwnerLongName());
     repModel.setPrimaryObjRef(objectReferenceAssembler.toModel(task.getPrimaryObjRef()));
+    repModel.setSecondaryObjectReferences(
+        task.getSecondaryObjectReferences().stream()
+            .map(objectReferenceAssembler::toModel)
+            .collect(Collectors.toList()));
     repModel.setRead(task.isRead());
     repModel.setTransferred(task.isTransferred());
     repModel.setAttachments(
@@ -164,6 +168,10 @@ public class TaskRepresentationModelAssembler
         repModel.getAttachments().stream()
             .map(attachmentAssembler::toEntityModel)
             .collect(Collectors.toList()));
+    task.setSecondaryObjectReferences(
+        repModel.getSecondaryObjectReferences().stream()
+            .map(objectReferenceAssembler::toEntity)
+            .collect(Collectors.toList()));
     task.setCustomAttributeMap(
         repModel.getCustomAttributes().stream()
             .collect(Collectors.toMap(CustomAttribute::getKey, CustomAttribute::getValue)));

rest/taskana-rest-spring/src/main/java/pro/taskana/task/rest/assembler/TaskSummaryRepresentationModelAssembler.java

@@ -75,6 +75,10 @@ public class TaskSummaryRepresentationModelAssembler
     repModel.setOwner(taskSummary.getOwner());
     repModel.setOwnerLongName(taskSummary.getOwnerLongName());
     repModel.setPrimaryObjRef(objectReferenceAssembler.toModel(taskSummary.getPrimaryObjRef()));
+    repModel.setSecondaryObjectReferences(
+        taskSummary.getSecondaryObjectReferences().stream()
+            .map(objectReferenceAssembler::toModel)
+            .collect(Collectors.toList()));
     repModel.setRead(taskSummary.isRead());
     repModel.setTransferred(taskSummary.isTransferred());
     repModel.setAttachmentSummaries(
@@ -128,6 +132,10 @@ public class TaskSummaryRepresentationModelAssembler
     taskSummary.setOwner(repModel.getOwner());
     taskSummary.setOwnerLongName(repModel.getOwnerLongName());
     taskSummary.setPrimaryObjRef(objectReferenceAssembler.toEntity(repModel.getPrimaryObjRef()));
+    taskSummary.setSecondaryObjectReferences(
+        repModel.getSecondaryObjectReferences().stream()
+            .map(objectReferenceAssembler::toEntity)
+            .collect(Collectors.toList()));
     taskSummary.setRead(repModel.isRead());
     taskSummary.setTransferred(repModel.isTransferred());
     taskSummary.setAttachmentSummaries(

rest/taskana-rest-spring/src/main/java/pro/taskana/task/rest/models/ObjectReferenceRepresentationModel.java

@@ -7,6 +7,9 @@ public class ObjectReferenceRepresentationModel
 
   /** Unique ID. */
   private String id;
+
+  /** Task Id. */
+  private String taskId;
   /** The company the referenced primary object belongs to. */
   private String company;
   /** The (kind of) system, the referenced primary object resides in (e.g. SAP, MySystem A, ...). */
@@ -26,6 +29,14 @@ public class ObjectReferenceRepresentationModel
     this.id = id;
   }
 
+  public String getTaskId() {
+    return taskId;
+  }
+
+  public void setTaskId(String taskId) {
+    this.taskId = taskId;
+  }
+
   public String getCompany() {
     return company;
   }

rest/taskana-rest-spring/src/main/java/pro/taskana/task/rest/models/TaskSummaryRepresentationModel.java

@@ -106,6 +106,8 @@ public class TaskSummaryRepresentationModel
   protected String custom15;
   /** A custom property with name "16". */
   protected String custom16;
+  /** Secondary object references of the task. */
+  protected List<ObjectReferenceRepresentationModel> secondaryObjectReferences = new ArrayList<>();
   /** The attachment summaries of this task. */
   private List<AttachmentSummaryRepresentationModel> attachmentSummaries = new ArrayList<>();
 
@@ -286,6 +288,15 @@ public class TaskSummaryRepresentationModel
     this.primaryObjRef = primaryObjRef;
   }
 
+  public List<ObjectReferenceRepresentationModel> getSecondaryObjectReferences() {
+    return secondaryObjectReferences;
+  }
+
+  public void setSecondaryObjectReferences(
+      List<ObjectReferenceRepresentationModel> secondaryObjectReferences) {
+    this.secondaryObjectReferences = secondaryObjectReferences;
+  }
+
   public boolean isRead() {
     return isRead;
   }

rest/taskana-rest-spring/src/test/java/pro/taskana/task/rest/TaskControllerIntTest.java

@@ -239,6 +239,51 @@ class TaskControllerIntTest {
     assertThat(response.getBody().getContent()).hasSize(4);
   }
 
+  @Test
+  void should_ReturnAllTasks_For_ProvidedSecondaryObjectReferenceByTypeAndValue() throws Exception {
+    String url =
+        restHelper.toUrl(RestEndpoints.URL_TASKS)
+            + "?sor="
+            + URLEncoder.encode("{\"type\":\"Type2\",\"value\":\"Value2\"}", "UTF-8");
+    HttpEntity<Object> auth = new HttpEntity<>(RestHelper.generateHeadersForUser("teamlead-1"));
+    ResponseEntity<TaskSummaryPagedRepresentationModel> response =
+        TEMPLATE.exchange(url, HttpMethod.GET, auth, TASK_SUMMARY_PAGE_MODEL_TYPE);
+    assertThat(response.getBody()).isNotNull();
+    assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
+    assertThat((response.getBody()).getLink(IanaLinkRelations.SELF)).isNotNull();
+    assertThat(response.getBody().getContent()).hasSize(2);
+  }
+
+  @Test
+  void should_ReturnAllTasks_For_ProvidedSecondaryObjectReferenceByCompany() throws Exception {
+    String url =
+        restHelper.toUrl(RestEndpoints.URL_TASKS)
+            + "?sor="
+            + URLEncoder.encode("{\"company\":\"Company3\"}", "UTF-8");
+    HttpEntity<Object> auth = new HttpEntity<>(RestHelper.generateHeadersForUser("teamlead-1"));
+    ResponseEntity<TaskSummaryPagedRepresentationModel> response =
+        TEMPLATE.exchange(url, HttpMethod.GET, auth, TASK_SUMMARY_PAGE_MODEL_TYPE);
+    assertThat(response.getBody()).isNotNull();
+    assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
+    assertThat((response.getBody()).getLink(IanaLinkRelations.SELF)).isNotNull();
+    assertThat(response.getBody().getContent()).hasSize(1);
+  }
+
+  @Test
+  void should_ReturnNoTasks_For_ProvidedNonexistentSecondaryObjectReference() throws Exception {
+    String url =
+        restHelper.toUrl(RestEndpoints.URL_TASKS)
+            + "?sor="
+            + URLEncoder.encode("{\"type\":\"Type2\",\"value\":\"Quatsch\"}", "UTF-8");
+    HttpEntity<Object> auth = new HttpEntity<>(RestHelper.generateHeadersForUser("teamlead-1"));
+    ResponseEntity<TaskSummaryPagedRepresentationModel> response =
+        TEMPLATE.exchange(url, HttpMethod.GET, auth, TASK_SUMMARY_PAGE_MODEL_TYPE);
+    assertThat(response.getBody()).isNotNull();
+    assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
+    assertThat((response.getBody()).getLink(IanaLinkRelations.SELF)).isNotNull();
+    assertThat(response.getBody().getContent()).isEmpty();
+  }
+
   @Test
   void should_ReturnAllTasksByWildcardSearch_For_ProvidedSearchValue() {
     String url =
@@ -579,6 +624,89 @@ class TaskControllerIntTest {
     assertThat(repModel.getAttachments()).isNotEmpty();
   }
 
+  @Test
+  void should_NotGetEmptyObjectReferencesList_When_GettingTaskWithObjectReferences() {
+    String url =
+        restHelper.toUrl(RestEndpoints.URL_TASKS_ID, "TKI:000000000000000000000000000000000001");
+    HttpEntity<Object> auth = new HttpEntity<>(RestHelper.generateHeadersForUser("admin"));
+
+    ResponseEntity<TaskRepresentationModel> response =
+        TEMPLATE.exchange(url, HttpMethod.GET, auth, TASK_MODEL_TYPE);
+
+    TaskRepresentationModel repModel = response.getBody();
+    assertThat(repModel).isNotNull();
+    assertThat(repModel.getSecondaryObjectReferences()).isNotEmpty();
+  }
+
+  @Test
+  void should_ReturnFilteredTasks_WhenGettingTasksBySecondaryObjectReferenceValue() {
+    String url = restHelper.toUrl(RestEndpoints.URL_TASKS) + "?sor-value=Value2";
+    HttpEntity<Object> auth = new HttpEntity<>(RestHelper.generateHeadersForUser("teamlead-1"));
+
+    ResponseEntity<TaskSummaryPagedRepresentationModel> response =
+        TEMPLATE.exchange(url, HttpMethod.GET, auth, TASK_SUMMARY_PAGE_MODEL_TYPE);
+
+    assertThat(response.getBody()).isNotNull();
+    assertThat((response.getBody()).getLink(IanaLinkRelations.SELF)).isNotNull();
+    assertThat(response.getBody().getContent()).hasSize(3);
+  }
+
+  @Test
+  void should_ReturnFilteredTasks_WhenGettingTasksBySecondaryObjectReferenceTypeLike() {
+    String url = restHelper.toUrl(RestEndpoints.URL_TASKS) + "?sor-type-like=Type";
+    HttpEntity<Object> auth = new HttpEntity<>(RestHelper.generateHeadersForUser("teamlead-1"));
+
+    ResponseEntity<TaskSummaryPagedRepresentationModel> response =
+        TEMPLATE.exchange(url, HttpMethod.GET, auth, TASK_SUMMARY_PAGE_MODEL_TYPE);
+
+    assertThat(response.getBody()).isNotNull();
+    assertThat((response.getBody()).getLink(IanaLinkRelations.SELF)).isNotNull();
+    assertThat(response.getBody().getContent()).hasSize(3);
+  }
+
+  @Test
+  void should_ReturnFilteredTasks_WhenGettingTasksBySecondaryObjectReferenceValueAndCompany() {
+    String url =
+        restHelper.toUrl(RestEndpoints.URL_TASKS) + "?sor-value=Value2&&sor-company=Company1";
+    HttpEntity<Object> auth = new HttpEntity<>(RestHelper.generateHeadersForUser("teamlead-1"));
+
+    ResponseEntity<TaskSummaryPagedRepresentationModel> response =
+        TEMPLATE.exchange(url, HttpMethod.GET, auth, TASK_SUMMARY_PAGE_MODEL_TYPE);
+
+    assertThat(response.getBody()).isNotNull();
+    assertThat((response.getBody()).getLink(IanaLinkRelations.SELF)).isNotNull();
+    assertThat(response.getBody().getContent()).hasSize(1);
+  }
+
+  @Test
+  void should_CreateAndDeleteTaskWithObjectReferences_WhenSpecifyingObjectReferences() {
+    TaskRepresentationModel taskRepresentationModel = getTaskResourceSample();
+    ObjectReferenceRepresentationModel obj0 = getSampleSecondaryObjectReference("0");
+    obj0.setTaskId(taskRepresentationModel.getTaskId());
+    ObjectReferenceRepresentationModel obj1 = getSampleSecondaryObjectReference("1");
+    obj1.setTaskId(taskRepresentationModel.getTaskId());
+    List<ObjectReferenceRepresentationModel> secondaryObjectReferences = List.of(obj0, obj1);
+    taskRepresentationModel.setSecondaryObjectReferences(secondaryObjectReferences);
+
+    String url = restHelper.toUrl(RestEndpoints.URL_TASKS);
+    HttpEntity<TaskRepresentationModel> auth =
+        new HttpEntity<>(taskRepresentationModel, RestHelper.generateHeadersForUser("teamlead-1"));
+
+    ResponseEntity<TaskRepresentationModel> responseCreate =
+        TEMPLATE.exchange(url, HttpMethod.POST, auth, TASK_MODEL_TYPE);
+    assertThat(responseCreate.getStatusCode()).isEqualTo(HttpStatus.CREATED);
+    assertThat(responseCreate.getBody()).isNotNull();
+    String taskIdOfCreatedTask = responseCreate.getBody().getTaskId();
+
+    String url2 = restHelper.toUrl(RestEndpoints.URL_TASKS_ID, taskIdOfCreatedTask);
+    HttpEntity<Object> auth2 = new HttpEntity<>(RestHelper.generateHeadersForUser("admin"));
+
+    ResponseEntity<TaskRepresentationModel> responseDeleted =
+        TEMPLATE.exchange(
+            url2, HttpMethod.DELETE, auth2, ParameterizedTypeReference.forType(Void.class));
+    assertThat(responseDeleted.getStatusCode()).isEqualTo(HttpStatus.NO_CONTENT);
+  }
+
   @Test
   void should_ReturnReceivedDate_When_GettingTask() {
     String url =
@@ -1029,4 +1157,14 @@ class TaskControllerIntTest {
     taskRepresentationModel.setPrimaryObjRef(objectReference);
     return taskRepresentationModel;
   }
+
+  private ObjectReferenceRepresentationModel getSampleSecondaryObjectReference(String suffix) {
+    ObjectReferenceRepresentationModel objectReference = new ObjectReferenceRepresentationModel();
+    objectReference.setCompany("SecondaryCompany" + suffix);
+    objectReference.setSystem("SecondarySystem" + suffix);
+    objectReference.setSystemInstance("SecondaryInstance" + suffix);
+    objectReference.setType("SecondaryType" + suffix);
+    objectReference.setValue("0000000" + suffix);
+    return objectReference;
+  }
 }

rest/taskana-rest-spring/src/test/java/pro/taskana/task/rest/TaskControllerRestDocTest.java

@@ -16,8 +16,8 @@ import pro.taskana.common.test.rest.RestHelper;
 import pro.taskana.common.test.security.JaasExtension;
 import pro.taskana.common.test.security.WithAccessId;
 import pro.taskana.task.api.TaskService;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.rest.assembler.TaskRepresentationModelAssembler;
 import pro.taskana.task.rest.models.TaskRepresentationModel;
 
@@ -106,7 +106,7 @@ class TaskControllerRestDocTest extends BaseRestDocTest {
   @Test
   void createTaskDocTest() throws Exception {
     final Task task = taskService.newTask("WBI:100000000000000000000000000000000004");
-    ObjectReference objectReference = new ObjectReference();
+    ObjectReferenceImpl objectReference = new ObjectReferenceImpl();
     objectReference.setCompany("MyCompany1");
     objectReference.setSystem("MySystem1");
     objectReference.setSystemInstance("MyInstance1");
@@ -114,6 +114,7 @@ class TaskControllerRestDocTest extends BaseRestDocTest {
     objectReference.setValue("00000001");
     task.setPrimaryObjRef(objectReference);
     task.setClassificationKey("L11010");
+    task.addSecondaryObjectReference("company", "system", "systemInstance", "type", "value");
     TaskRepresentationModel repModel = assembler.toModel(task);
     mockMvc
         .perform(post(RestEndpoints.URL_TASKS).content(objectMapper.writeValueAsString(repModel)))

rest/taskana-rest-spring/src/test/java/pro/taskana/task/rest/assembler/AttachmentRepresentationModelAssemblerTest.java

@@ -13,8 +13,8 @@ import pro.taskana.classification.rest.models.ClassificationSummaryRepresentatio
 import pro.taskana.common.test.rest.TaskanaSpringBootTest;
 import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.models.Attachment;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.internal.models.AttachmentImpl;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.rest.models.AttachmentRepresentationModel;
 import pro.taskana.task.rest.models.ObjectReferenceRepresentationModel;
 
@@ -64,7 +64,7 @@ class AttachmentRepresentationModelAssemblerTest {
   @Test
   void should_ReturnRepresentationModel_When_ConvertingEntityToRepresentationModel() {
     AttachmentImpl attachment = (AttachmentImpl) taskService.newAttachment();
-    ObjectReference reference = new ObjectReference();
+    ObjectReferenceImpl reference = new ObjectReferenceImpl();
     ClassificationSummary summary =
         classService.newClassification("ckey", "cdomain", "MANUAL").asSummary();
     reference.setId("abc");
@@ -87,7 +87,7 @@ class AttachmentRepresentationModelAssemblerTest {
   @Test
   void should_Equal_When_ComparingEntityWithConvertedEntity() {
     AttachmentImpl attachment = (AttachmentImpl) taskService.newAttachment();
-    ObjectReference reference = new ObjectReference();
+    ObjectReferenceImpl reference = new ObjectReferenceImpl();
     ClassificationSummary summary =
         classService.newClassification("ckey", "cdomain", "MANUAL").asSummary();
     reference.setId("abc");

rest/taskana-rest-spring/src/test/java/pro/taskana/task/rest/assembler/AttachmentSummaryRepresentationModelAssemblerTest.java

@@ -12,8 +12,8 @@ import pro.taskana.classification.rest.models.ClassificationSummaryRepresentatio
 import pro.taskana.common.test.rest.TaskanaSpringBootTest;
 import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.models.AttachmentSummary;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.internal.models.AttachmentSummaryImpl;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.rest.models.AttachmentSummaryRepresentationModel;
 import pro.taskana.task.rest.models.ObjectReferenceRepresentationModel;
 
@@ -63,7 +63,7 @@ class AttachmentSummaryRepresentationModelAssemblerTest {
   void should_ReturnRepresentationModel_When_ConvertingEntityToRepresentationModel() {
     AttachmentSummaryImpl attachment =
         (AttachmentSummaryImpl) taskService.newAttachment().asSummary();
-    ObjectReference reference = new ObjectReference();
+    ObjectReferenceImpl reference = new ObjectReferenceImpl();
     ClassificationSummary summary =
         classService.newClassification("ckey", "cdomain", "MANUAL").asSummary();
     reference.setId("abc");
@@ -86,7 +86,7 @@ class AttachmentSummaryRepresentationModelAssemblerTest {
   void should_Equal_When_ComparingEntityWithConvertedEntity() {
     AttachmentSummaryImpl attachment =
         (AttachmentSummaryImpl) taskService.newAttachment().asSummary();
-    ObjectReference reference = new ObjectReference();
+    ObjectReferenceImpl reference = new ObjectReferenceImpl();
     ClassificationSummary summary =
         classService.newClassification("ckey", "cdomain", "MANUAL").asSummary();
     reference.setId("abc");

rest/taskana-rest-spring/src/test/java/pro/taskana/task/rest/assembler/ObjectReferenceRepresentationModelAssemblerTest.java

@@ -7,6 +7,7 @@ import org.springframework.beans.factory.annotation.Autowired;
 
 import pro.taskana.common.test.rest.TaskanaSpringBootTest;
 import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.rest.models.ObjectReferenceRepresentationModel;
 
 @TaskanaSpringBootTest
@@ -37,7 +38,7 @@ class ObjectReferenceRepresentationModelAssemblerTest {
 
   @Test
   void should_ReturnRepresentationModel_When_ConvertingEntityToRepresentationModel() {
-    ObjectReference entity = new ObjectReference();
+    ObjectReferenceImpl entity = new ObjectReferenceImpl();
     entity.setId("id");
     entity.setValue("value");
     entity.setType("type");

rest/taskana-rest-spring/src/test/java/pro/taskana/task/rest/assembler/TaskRepresentationModelAssemblerTest.java

@@ -18,9 +18,9 @@ import pro.taskana.task.api.TaskCustomField;
 import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.TaskState;
 import pro.taskana.task.api.models.Attachment;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.Task;
 import pro.taskana.task.internal.models.AttachmentImpl;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.internal.models.TaskImpl;
 import pro.taskana.task.rest.models.AttachmentRepresentationModel;
 import pro.taskana.task.rest.models.ObjectReferenceRepresentationModel;
@@ -152,7 +152,7 @@ class TaskRepresentationModelAssemblerTest {
   void should_ReturnRepresentationModel_When_ConvertingEntityToRepresentationModel()
       throws Exception {
     // given
-    ObjectReference primaryObjRef = new ObjectReference();
+    ObjectReferenceImpl primaryObjRef = new ObjectReferenceImpl();
     primaryObjRef.setId("abc");
     final Workbasket workbasket = workbasketService.newWorkbasket("key", "domain");
     ClassificationSummary classification =
@@ -215,7 +215,7 @@ class TaskRepresentationModelAssemblerTest {
   @Test
   void should_Equal_When_ComparingEntityWithConvertedEntity() throws InvalidArgumentException {
     // given
-    ObjectReference primaryObjRef = new ObjectReference();
+    ObjectReferenceImpl primaryObjRef = new ObjectReferenceImpl();
     primaryObjRef.setId("abc");
     final WorkbasketSummary workbasket =
         workbasketService.newWorkbasket("key", "domain").asSummary();

rest/taskana-rest-spring/src/test/java/pro/taskana/task/rest/assembler/TaskSummaryRepresentationModelAssemblerTest.java

@@ -30,9 +30,9 @@ import pro.taskana.common.test.rest.TaskanaSpringBootTest;
 import pro.taskana.task.api.TaskService;
 import pro.taskana.task.api.TaskState;
 import pro.taskana.task.api.models.AttachmentSummary;
-import pro.taskana.task.api.models.ObjectReference;
 import pro.taskana.task.api.models.TaskSummary;
 import pro.taskana.task.internal.models.AttachmentSummaryImpl;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 import pro.taskana.task.internal.models.TaskSummaryImpl;
 import pro.taskana.task.rest.models.AttachmentRepresentationModel;
 import pro.taskana.task.rest.models.AttachmentSummaryRepresentationModel;
@@ -66,7 +66,7 @@ class TaskSummaryRepresentationModelAssemblerTest {
   @Test
   void should_ReturnRepresentationModel_When_ConvertingEntityToRepresentationModel()
       throws Exception {
-    ObjectReference primaryObjRef = new ObjectReference();
+    ObjectReferenceImpl primaryObjRef = new ObjectReferenceImpl();
     primaryObjRef.setId("abc");
     ClassificationSummary classification =
         this.classificationService.newClassification("ckey", "cdomain", "MANUAL").asSummary();
@@ -222,7 +222,7 @@ class TaskSummaryRepresentationModelAssemblerTest {
   @Test
   void should_Equal_When_ComparingEntityWithConvertedEntity() {
     // given
-    ObjectReference primaryObjRef = new ObjectReference();
+    ObjectReferenceImpl primaryObjRef = new ObjectReferenceImpl();
     primaryObjRef.setId("abc");
     final WorkbasketSummary workbasket =
         workbasketService.newWorkbasket("key", "domain").asSummary();
@@ -335,7 +335,7 @@ class TaskSummaryRepresentationModelAssemblerTest {
   private static void testEqualityAttachments(
       List<AttachmentSummary> attachmentSummaries,
       List<AttachmentSummaryRepresentationModel> resources) {
-    assertThat(attachmentSummaries.size()).isEqualTo(resources.size());
+    assertThat(attachmentSummaries).hasSameSizeAs(resources);
 
     for (int i = 0; i < resources.size(); ++i) {
       AttachmentSummaryRepresentationModel resource = resources.get(i);

routing/taskana-spi-routing-dmn-router/src/test/java/pro/taskana/AbstractAccTest.java

@@ -10,6 +10,7 @@ import pro.taskana.common.internal.configuration.DbSchemaCreator;
 import pro.taskana.common.test.config.DataSourceGenerator;
 import pro.taskana.sampledata.SampleDataGenerator;
 import pro.taskana.task.api.models.ObjectReference;
+import pro.taskana.task.internal.models.ObjectReferenceImpl;
 
 public abstract class AbstractAccTest {
 
@@ -45,7 +46,7 @@ public abstract class AbstractAccTest {
 
   protected ObjectReference createObjectReference(
       String company, String system, String systemInstance, String type, String value) {
-    ObjectReference objectReference = new ObjectReference();
+    ObjectReferenceImpl objectReference = new ObjectReferenceImpl();
     objectReference.setCompany(company);
     objectReference.setSystem(system);
     objectReference.setSystemInstance(systemInstance);

web/src/app/workplace/components/task-details/task-details.component.ts

@@ -6,12 +6,12 @@ import { TaskService } from 'app/workplace/services/task.service';
 import { Task } from 'app/workplace/models/task';
 import { RequestInProgressService } from 'app/shared/services/request-in-progress/request-in-progress.service';
 import { TaskanaDate } from 'app/shared/util/taskana.date';
-import { ObjectReference } from 'app/workplace/models/object-reference';
 import { Workbasket } from 'app/shared/models/workbasket';
 import { WorkplaceService } from 'app/workplace/services/workplace.service';
 import { MasterAndDetailService } from 'app/shared/services/master-and-detail/master-and-detail.service';
 import { NotificationService } from '../../../shared/services/notifications/notification.service';
 import { take, takeUntil } from 'rxjs/operators';
+import { ObjectReference } from '../../models/object-reference';
 
 @Component({
   selector: 'taskana-task-details',
@@ -186,7 +186,10 @@ export class TaskDetailsComponent implements OnInit, OnDestroy {
         this.task = task;
         this.taskService.selectTask(this.task);
         this.taskService.publishUpdatedTask(task);
-        this.router.navigate([`../${task.taskId}`], { relativeTo: this.route, queryParamsHandling: 'merge' });
+        this.router.navigate([`../${task.taskId}`], {
+          relativeTo: this.route,
+          queryParamsHandling: 'merge'
+        });
       },
       () => {
         this.requestInProgressService.setRequestInProgress(false);

web/src/app/workplace/models/task.ts

@@ -5,7 +5,7 @@ import { ClassificationSummary } from '../../shared/models/classification-summar
 export class Task {
   constructor(
     public taskId: string,
-    public primaryObjRef: ObjectReference = new ObjectReference(),
+    public primaryObjRef?: ObjectReference,
     public workbasketSummary?: Workbasket,
     public classificationSummary?: ClassificationSummary,
     public businessProcessId?: string,