Since transaction rollback is not supported in WebSphereExtendedJtaPlatform it throws below exception and the root cause exception from transactionCoordinator.getTransactionContext().managedFlush() is forgotten.

WTRN0074E: Exception caught from before_completion synchronization operation: java.lang.UnsupportedOperationException
at org.hibernate.service.jta.platform.internal.WebSphereExtendedJtaPlatform$TransactionManagerAdapter.setRollbackOnly(WebSphereExtendedJtaPlatform.java:139)
at org.hibernate.engine.transaction.internal.jta.CMTTransaction.markRollbackOnly(CMTTransaction.java:131)
at org.hibernate.engine.transaction.internal.TransactionCoordinatorImpl.setRollbackOnly(TransactionCoordinatorImpl.java:321)
at org.hibernate.engine.transaction.synchronization.internal.SynchronizationCallbackCoordinatorNonTrackingImpl.setRollbackOnly(SynchronizationCallbackCoordinatorNonTrackingImpl.java:119)
at org.hibernate.engine.transaction.synchronization.internal.SynchronizationCallbackCoordinatorNonTrackingImpl.beforeCompletion(SynchronizationCallbackCoordinatorNonTrackingImpl.java:109)
at org.hibernate.engine.transaction.synchronization.internal.RegisteredSynchronization.beforeCompletion(RegisteredSynchronization.java:53)
at org.hibernate.service.jta.platform.internal.WebSphereExtendedJtaPlatform$TransactionManagerAdapter$TransactionAdapter$1.invoke(WebSphereExtendedJtaPlatform.java:176)
at com.sun.proxy.$Proxy96.beforeCompletion(Unknown Source)
at com.ibm.ws.jtaextensions.SynchronizationCallbackWrapper.beforeCompletion(SynchronizationCallbackWrapper.java:66)
at com.ibm.tx.jta.impl.RegisteredSyncs.coreDistributeBefore(RegisteredSyncs.java:291)
at com.ibm.ws.tx.jta.RegisteredSyncs.distributeBefore(RegisteredSyncs.java:153)
at com.ibm.ws.tx.jta.TransactionImpl.prePrepare(TransactionImpl.java:2384)
at com.ibm.ws.tx.jta.TransactionImpl.stage1CommitProcessing(TransactionImpl.java:588)
at com.ibm.tx.jta.impl.TransactionImpl.processCommit(TransactionImpl.java:1029)
at com.ibm.tx.jta.impl.TransactionImpl.commit(TransactionImpl.java:963)
at com.ibm.ws.tx.jta.TranManagerImpl.commit(TranManagerImpl.java:439)
at com.ibm.tx.jta.impl.TranManagerSet.commit(TranManagerSet.java:191)
at com.ibm.ws.tx.jta.UserTransactionImpl.commit(UserTransactionImpl.java:302)
at org.springframework.transaction.jta.JtaTransactionManager.doCommit(JtaTransactionManager.java:1021)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:757)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:726)