HHH-13760 causes regression under specific conditions.
When entityManager.clear() is called in a JTA transaction with FlushMode.MANUAL, the changed entity must have a @ManyToOne Lazy reference and must add or remove an item from the @OneToMany collection.
An error occures after entityManager.close() and commit (simulates spring jta transaction).

...
Caused by: org.hibernate.LazyInitializationException: could not initialize proxy org.hibernate.envers.test.entities.onetomany.SetRefIngEntity#3 - no Session
at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:170)
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:310)
at org.hibernate.envers.internal.entities.mapper.relation.ToOneIdMapper.mapToMapFromEntity(ToOneIdMapper.java:62)
at org.hibernate.envers.internal.entities.mapper.MultiPropertyMapper$1.run(MultiPropertyMapper.java:137)
at org.hibernate.envers.internal.entities.mapper.MultiPropertyMapper$1.run(MultiPropertyMapper.java:105)
at java.security.AccessController.doPrivileged(Native Method)
at org.hibernate.envers.internal.entities.mapper.MultiPropertyMapper.mapToMapFromEntity(MultiPropertyMapper.java:104)
at org.hibernate.envers.internal.synchronization.work.CollectionChangeWorkUnit.generateData(CollectionChangeWorkUnit.java:54)
at org.hibernate.envers.internal.synchronization.work.AbstractAuditWorkUnit.perform(AbstractAuditWorkUnit.java:66)
at org.hibernate.envers.internal.synchronization.AuditProcess.executeInSession(AuditProcess.java:125)
at org.hibernate.envers.internal.synchronization.AuditProcess.doBeforeTransactionCompletion(AuditProcess.java:164)
at org.hibernate.envers.internal.synchronization.AuditProcessManager$1.doBeforeTransactionCompletion(AuditProcessManager.java:47)
at org.hibernate.engine.spi.ActionQueue$BeforeTransactionCompletionProcessQueue.beforeTransactionCompletion(ActionQueue.java:954)
at org.hibernate.engine.spi.ActionQueue.beforeTransactionCompletion(ActionQueue.java:525)
at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2379)
at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:447)
at org.hibernate.resource.transaction.backend.jta.internal.JtaTransactionCoordinatorImpl.beforeCompletion(JtaTransactionCoordinatorImpl.java:355)
at org.hibernate.resource.transaction.backend.jta.internal.synchronization.SynchronizationCallbackCoordinatorNonTrackingImpl.beforeCompletion(SynchronizationCallbackCoordinatorNonTrackingImpl.java:47)
at org.hibernate.resource.transaction.backend.jta.internal.synchronization.RegisteredSynchronization.beforeCompletion(RegisteredSynchronization.java:37)
at com.arjuna.ats.internal.jta.resources.arjunacore.SynchronizationImple.beforeCompletion(SynchronizationImple.java:76)
at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.beforeCompletion(TwoPhaseCoordinator.java:273)
at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.end(TwoPhaseCoordinator.java:93)
at com.arjuna.ats.arjuna.AtomicAction.commit(AtomicAction.java:164)
at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1165)
... 61 more

However, I'm not sure if the call to entityManager.close () is used correctly in this context.