org.springframework.transaction.TransactionSystemException: Could not commit JPA transaction; nested exception is javax.persistence.RollbackException: Error while committing the transaction

	at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:526)
	at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:761)
	at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:730)
	at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:150)
	at com.bbh.infonav.calc.core.command.config.integration.nav.NavCalculationIntegrationTest.calculate already calculated fund NAV(NavCalculationIntegrationTest.groovy:195)
Caused by: javax.persistence.RollbackException: Error while committing the transaction
	at org.hibernate.internal.ExceptionConverterImpl.convertCommitException(ExceptionConverterImpl.java:75)
	at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:71)
	at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:517)
	... 4 more
Caused by: java.lang.NullPointerException
	at org.hibernate.event.internal.AbstractFlushingEventListener.prepareEntityFlushes(AbstractFlushingEventListener.java:138)
	at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:74)
	at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:38)
	at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1428)
	at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:484)
	at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3190)
	at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2404)
	at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:467)
	at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:146)
	at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$100(JdbcResourceLocalTransactionCoordinatorImpl.java:38)
	at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:220)
	at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:68)
	... 5 more