code: private static <K, V> Map<K, V> filterFiltered(
        AbstractFilteredMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
      return new FilteredEntryMap<>(
          map.unfiltered, Predicates.<Entry<K, V>>and(map.predicate, entryPredicate));
    }
docs: Support {@code clear()}, {@code removeAll()}, and {@code retainAll()} when filtering a filtered
  map.