if (unfiltered instanceof FilteredKeyListMultimap) {
      FilteredKeyListMultimap<K, V> prev = (FilteredKeyListMultimap<K, V>) unfiltered;
      return new FilteredKeyListMultimap<>(
          prev.unfiltered(), Predicates.and(prev.keyPredicate, keyPredicate));
    } else {
      return new FilteredKeyListMultimap<>(unfiltered, keyPredicate);
    }
  }

  /**