code: @Test public void should_return_null_and_not_wrapper_for_null_values() throws Exception {
    CompleteBean entity=CompleteBeanTestBuilder.builder().randomId().name("DuyHai").buid();
    entity.setFriends(null);
    entity.setFollowers(null);
    entity.setPreferences(null);
    manager.persist(entity);
    entity=manager.find(CompleteBean.class,entity.getId());
    assertThat(entity.getFriends()).isNotNull().isInstanceOf(ListWrapper.class).isEmpty();
    assertThat(entity.getFollowers()).isNull();
    assertThat(entity.getPreferences()).isNull();
    assertThat(entity.getLabel()).isNull();
    assertThat(entity.getAge()).isNull();
  }
  