code: @Test public void should_mark_dirty_on_add_all() throws Exception {
    List<Object> target=new ArrayList<>();
    ListWrapper wrapper=prepareListWrapper(target);
    Collection<String> list=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(APPEND_TO_LIST);
    assertThat(changeSet.getPropertyMeta()).isEqualTo(propertyMeta);
    assertThat(changeSet.getRawListChanges()).containsOnly("a","b");
  }
  