프록시 강의 38:45초 질문드립니다.

            Member member1 = new Member();
            member1.setUsername("hello");
            em.persist(member1);

            em.flush();
            em.clear();

            Member reference = em.getReference(Member.class, member1.getId()); // 영속성 컨텍스트에서 가져옴
            System.out.println("reference.getClass() = " + reference.getClass());

//            em.detach(reference);
            em.close();

            System.out.println("reference.getUsername() = " + reference.getUsername());