code: @Test public void should_mark_dirty_on_add_all() throws Exception {
    Set<Object> target=new HashSet<>();
    SetWrapper wrapper=prepareSetWrapper(target);
    Collection<String> list=Arrays.asList("a","b");
    wrapper.setProxifier(proxifier);
    when(proxifier.removeProxy(Mockito.<Collection<String>>any())).thenReturn(list);
    wrapper.addAll(list);
    DirtyChecker dirtyChecker=dirtyMap.get(setter);
    assertThat(dirtyChecker.getPropertyMeta()).isEqualTo(propertyMeta);
    DirtyCheckChangeSet changeSet=dirtyChecker.getChangeSets().get(0);
    assertThat(changeSet.getChangeType()).isEqualTo(ADD_TO_SET);
    assertThat(changeSet.getPropertyMeta()).isEqualTo(propertyMeta);
    assertThat(changeSet.getRawSetChanges()).containsOnly("a","b");
  }
  