Message Title

The issue is that it's not possible with recent Hibernate 5.x versions to customize the unique key name on a many-to-one association with the unique-key attribute that has also a orphan delete cascading. (The upcoming attachment has a complete test case)

<many-to-one cascade="all-delete-orphan" entity-name="TestWorkflowItem" column="next_id" unique-key="uk_nextid" name="next" foreign-key="fk_testworkflowitem_workflowitem"/>

org.hibernate.testing.junit4.CallbackException: org.hibernate.testing.junit4.BaseCoreFunctionalTestCase#buildSessionFactory
        at org.hibernate.testing.junit4.TestClassMetadata.performCallbackInvocation(TestClassMetadata.java:203)
        at org.hibernate.testing.junit4.TestClassMetadata.invokeCallback(TestClassMetadata.java:187)
        at org.hibernate.testing.junit4.TestClassMetadata.performCallbacks(TestClassMetadata.java:181)
        at org.hibernate.testing.junit4.TestClassMetadata.performBeforeClassCallbacks(TestClassMetadata.java:172)
        at org.hibernate.testing.junit4.BeforeClassCallbackHandler.evaluate(BeforeClassCallbackHandler.java:25)
        at org.hibernate.testing.junit4.AfterClassCallbackHandler.evaluate(AfterClassCallbackHandler.java:25)
        at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
        at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:252)
        at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:141)
        at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:112)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:189)
        at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:165)
        at org.apache.maven.surefire.booter.ProviderFactory.invokeProvider(ProviderFactory.java:85)
        at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:115)
        at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:75)
Caused by: org.hibernate.boot.MappingException: many-to-one attribute [TestWorkflowItem.next] specified delete-orphan but is not specified as unique; remove delete-orphan cascading or specify unique="true" : origin(org/hibernate/test/TestWorkflowItem
.hbm.xml)
        at org.hibernate.boot.model.source.internal.hbm.ModelBinder.createManyToOneAttribute(ModelBinder.java:2174)
        at org.hibernate.boot.model.source.internal.hbm.ModelBinder.bindAllEntityAttributes(ModelBinder.java:1215)
        at org.hibernate.boot.model.source.internal.hbm.ModelBinder.bindRootEntity(ModelBinder.java:264)
        at org.hibernate.boot.model.source.internal.hbm.ModelBinder.bindEntityHierarchy(ModelBinder.java:184)
        at org.hibernate.boot.model.source.internal.hbm.HbmMetadataSourceProcessorImpl.processEntityHierarchies(HbmMetadataSourceProcessorImpl.java:144)
        at org.hibernate.boot.model.process.spi.MetadataBuildingProcess$1.processEntityHierarchies(MetadataBuildingProcess.java:218)
        at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:265)
        at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83)
        at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418)
        at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87)
        at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:692)
        at org.hibernate.testing.junit4.BaseCoreFunctionalTestCase.buildSessionFactory(BaseCoreFunctionalTestCase.java:107)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.hibernate.testing.junit4.TestClassMetadata.performCallbackInvocation(TestClassMetadata.java:200)
        ... 18 more

If the many-to-one mapping is changed to also include unique="true", the mapping exception goes away, but the specified unique key name "uk_nextid" is ignored and not used. Instead an auto-generated key name is used: