OptimisticLockException.java

// EntityManager and transaction 1
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
		
// EntityManager and transaction 2
EntityManager em2 = emf.createEntityManager();
em2.getTransaction().begin();

// update 1
Author a = em.find(Author.class, 1L);
a.setFirstName("changed");
		
// update 2
Author a2 = em2.find(Author.class, 1L);
a2.setFirstName("changed");

// commit transaction 1
em.getTransaction().commit();
em.close();
		
// commit transaction 2
try {
	em2.getTransaction().commit();
	Assert.fail();
	} catch (RollbackException e) {
		Assert.assertTrue(e.getCause() instanceof OptimisticLockException);
		log.info("2nd transaction failed with an OptimisticLockException");
	}
		
em2.close();