@Override
  protected synchronized @Nullable Collection<LanguageRef> getFilterItems() {
    final Collection<LanguageRef> result = super.getFilterItems();
    if (result == null) {
      return null;
    }
    final Collection<LanguageRef> items = new HashSet<>(result);
    items.add(LanguageRef.forLanguage(Language.ANY));
    return items;
  }
@Override
  protected synchronized @Nullable Collection<LanguageRef> getFilterItems()