eclipseLink saving new objects in manyToOne relationship even when no Cascade.PERSIST - jpa

Question

I have this situation
public class A {
#ManyToOne(cascade = { CascadeType.REFRESH })
#JoinColumn(name = "COLUMN_B_ID", insertable = false, updatable = false)
private B testB;
}
I would think that no matter what changes are made to the property testB in class A, it would not be persisted. However, when I do the following
A testA = new A();
a.setTestB(new B());
save(testA);
eclipseLink tries to persist testB first before persisting testA. I would think that since the ManyToOne mapping on testB is not set to CascadeType.PERSIST and since insertable and updateable are false, any attempt to set a new instance of B on A would not work while saving A but I am seeing the contrary. Any idea what could be wrong? Is there a way to prevent this?

Answer 1

I'm testing code below against Eclipselink 2.2.1 and it throws an exception demanding CascadeType.PERSIST to be present:
Caused by: java.lang.IllegalStateException: During synchronization a new object
was found through a relationship that was not marked cascade PERSIST: eclipselin
k.saving.neww.objects.in.manytoone.relationship.even.when.no.cascade.B#109f188a.
With Eclipselink 2.5.1 there is the same exception:
Caused by: java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST: test.B#6db66c18.
at org.eclipse.persistence.internal.sessions.RepeatableWriteUnitOfWork.discoverUnregisteredNewObjects(RepeatableWriteUnitOfWork.java:310)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.calculateChanges(UnitOfWorkImpl.java:723)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitToDatabaseWithChangeSet(UnitOfWorkImpl.java:1516)
at org.eclipse.persistence.internal.sessions.RepeatableWriteUnitOfWork.commitRootUnitOfWork(RepeatableWriteUnitOfWork.java:277)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitAndResume(UnitOfWorkImpl.java:1169)
at org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commit(EntityTransactionImpl.java:132)
A a = new A();
a.setTestB(new B());
em.persist(a);