em.getTransaction().begin();
em.persist(entity);
em.getTransaction().commit();
em.clear();
BookId id = new BookId();
id.setName(bookName);
id.setLibrary(libName);
Book persistedEntity = em.find(Book.class, id);
StateManagerImpl smi = ((StateManagerImpl) ((PersistenceCapable) persistedEntity).pcGetStateManager());
Object oid = smi.getObjectId();