private static void findDetachAndMergeEntity() {
EntityManager em = entityManagerFactory.createEntityManager();
Employee employee = em.find(Employee.class, 1);
System.out.println("after find(): " + em.contains(employee));
em.detach(employee);
System.out.println("after detach(): " + em.contains(employee));
employee = em.merge(employee);
System.out.println("after merging(): " + em.contains(employee));
em.close();
}