Set<E> unfiltered, Predicate<? super E> predicate) {
    if (unfiltered instanceof SortedSet) {
      return filter((SortedSet<E>) unfiltered, predicate);
    }
    if (unfiltered instanceof FilteredSet) {
      // Support clear(), removeAll(), and retainAll() when filtering a filtered
      // collection.
      FilteredSet<E> filtered = (FilteredSet<E>) unfiltered;

    extends FilteredKeyMultimap<K, V> implements ListMultimap<K, V> {
  FilteredKeyListMultimap(ListMultimap<K, V> unfiltered, Predicate<? super K> keyPredicate) {
    super(unfiltered, keyPredicate);
  }

  @Override
  public ListMultimap<K, V> unfiltered() {
    return (ListMultimap<K, V>) super.unfiltered();
  }

  @Override
  public List<V> get(@ParametricNullness K key) {
    return (List<V>) super.get(key);
  }

    Multimap<String, Integer> filtered = filterValues(unfiltered, VALUE_PREDICATE);
    assertEquals(1, filtered.size());
    assertFalse(filtered.containsEntry("foo", 55556));
    assertTrue(filtered.containsEntry("badkey", 1));
  }

  public void testFilterFiltered() {
    Multimap<String, Integer> unfiltered = HashMultimap.create();
    unfiltered.put("foo", 55556);
    unfiltered.put("badkey", 1);

    SortedMap<String, Integer> unfiltered = createUnfiltered();
    unfiltered.put("apple", 2);
    unfiltered.put("banana", 6);
    unfiltered.put("cat", 3);
    unfiltered.put("dog", 5);

    SortedMap<String, Integer> filtered = Maps.filterEntries(unfiltered, CORRECT_LENGTH);
    assertThat(filtered.firstKey()).isEqualTo("banana");
    assertThat(filtered.lastKey()).isEqualTo("cat");
  }

                List<String> unfiltered = new ArrayList<>();
                unfiltered.add("yyy");
                unfiltered.addAll(ImmutableList.copyOf(elements));
                unfiltered.add("zzz");
                unfiltered.add("abc");
                return Collections2.filter(Collections2.filter(unfiltered, LENGTH_1), NOT_YYY_ZZZ);
              }
            })

    final Collection<E> unfiltered;
    final Predicate<? super E> predicate;

    FilteredCollection(Collection<E> unfiltered, Predicate<? super E> predicate) {
      this.unfiltered = unfiltered;
      this.predicate = predicate;
    }

    FilteredCollection<E> createCombined(Predicate<? super E> newPredicate) {
      return new FilteredCollection<>(unfiltered, Predicates.and(predicate, newPredicate));
    }

  final Multimap<K, V> unfiltered;
  final Predicate<? super Entry<K, V>> predicate;

  FilteredEntryMultimap(Multimap<K, V> unfiltered, Predicate<? super Entry<K, V>> predicate) {
    this.unfiltered = checkNotNull(unfiltered);
    this.predicate = checkNotNull(predicate);
  }

  @Override
  public Multimap<K, V> unfiltered() {
    return unfiltered;
  }

  @Override

    super(true, true, false);
  }

  private Multimap<String, Integer> createMultimap() {
    Multimap<String, Integer> unfiltered = HashMultimap.create();
    unfiltered.put("zero", 55556);
    unfiltered.put("one", 55556);
    unfiltered.put("badkey", 1);
    return Multimaps.filterEntries(unfiltered, PREDICATE);
  }

  @Override
  protected Map<String, Collection<Integer>> makeEmptyMap() {

    super(true, true, false);
  }

  private Multimap<String, Integer> createMultimap() {
    Multimap<String, Integer> unfiltered = HashMultimap.create();
    unfiltered.put("zero", 55556);
    unfiltered.put("one", 55556);
    unfiltered.put("badkey", 1);
    return Multimaps.filterEntries(unfiltered, PREDICATE);
  }

  @Override
  protected Map<String, Collection<Integer>> makeEmptyMap() {

                List<String> unfiltered = new ArrayList<>();
                unfiltered.add("yyy");
                unfiltered.addAll(ImmutableList.copyOf(elements));
                unfiltered.add("zzz");
                unfiltered.add("abc");
                return Collections2.filter(Collections2.filter(unfiltered, LENGTH_1), NOT_YYY_ZZZ);
              }
            })