public void testNullTimestampVersion() {
EntityManager em = emf.createEntityManager();
EntityTransaction tran = em.getTransaction();
tran.begin();
em.persist(new TimestampVersion());
em.persist(new TimestampVersion());
tran.commit();
tran.begin();
em.createNativeQuery("UPDATE TimestampVersion set version = NULL").executeUpdate();
tran.commit();