checkNotNull(keyPredicate);
    Predicate<Entry<K, ?>> entryPredicate = keyPredicateOnEntries(keyPredicate);
    return (unfiltered instanceof AbstractFilteredMap)
        ? filterFiltered((AbstractFilteredMap<K, V>) unfiltered, entryPredicate)
        : new FilteredKeyMap<K, V>(checkNotNull(unfiltered), keyPredicate, entryPredicate);
  }

  /**

    checkNotNull(keyPredicate);
    Predicate<Entry<K, ?>> entryPredicate = keyPredicateOnEntries(keyPredicate);
    return (unfiltered instanceof AbstractFilteredMap)
        ? filterFiltered((AbstractFilteredMap<K, V>) unfiltered, entryPredicate)
        : new FilteredKeyMap<K, V>(checkNotNull(unfiltered), keyPredicate, entryPredicate);
  }

  /**

          prev.unfiltered, Predicates.and(prev.keyPredicate, keyPredicate));
    } else if (unfiltered instanceof FilteredMultimap) {
      FilteredMultimap<K, V> prev = (FilteredMultimap<K, V>) unfiltered;
      return filterFiltered(prev, Maps.keyPredicateOnEntries(keyPredicate));
    } else {
      return new FilteredKeyMultimap<>(unfiltered, keyPredicate);
    }
  }

  /**

          prev.unfiltered, Predicates.and(prev.keyPredicate, keyPredicate));
    } else if (unfiltered instanceof FilteredMultimap) {
      FilteredMultimap<K, V> prev = (FilteredMultimap<K, V>) unfiltered;
      return filterFiltered(prev, Maps.keyPredicateOnEntries(keyPredicate));
    } else {
      return new FilteredKeyMultimap<>(unfiltered, keyPredicate);
    }
  }

  /**