*
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
final class FilteredKeySetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends FilteredKeyMultimap<K, V> implements FilteredSetMultimap<K, V> {

  FilteredKeySetMultimap(SetMultimap<K, V> unfiltered, Predicate<? super K> keyPredicate) {
    super(unfiltered, keyPredicate);
  }

  @Override

      SetMultimap<K, V> filterKeys(
          SetMultimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
    if (unfiltered instanceof FilteredKeySetMultimap) {
      FilteredKeySetMultimap<K, V> prev = (FilteredKeySetMultimap<K, V>) unfiltered;
      return new FilteredKeySetMultimap<>(
          prev.unfiltered(), Predicates.<K>and(prev.keyPredicate, keyPredicate));
    } else if (unfiltered instanceof FilteredSetMultimap) {