unfiltered.put("one", 1);
    unfiltered.put("two", 2);
    unfiltered.put("three", 3);
    unfiltered.put("four", 4);
    Map<String, Integer> filtered = Maps.filterValues(unfiltered, EVEN);
    assertEquals(ImmutableMap.of("one", 1, "two", 2, "three", 3, "four", 4), unfiltered);
    assertEquals(ImmutableMap.of("two", 2, "four", 4), filtered);

    filtered.clear();

    unfiltered.put("one", 1);
    unfiltered.put("two", 2);
    unfiltered.put("three", 3);
    unfiltered.put("four", 4);
    Map<String, Integer> filtered = Maps.filterValues(unfiltered, EVEN);
    assertEquals(ImmutableMap.of("one", 1, "two", 2, "three", 3, "four", 4), unfiltered);
    assertEquals(ImmutableMap.of("two", 2, "four", 4), filtered);

    filtered.clear();

    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);

    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() {

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

  FilteredKeyMultimap(Multimap<K, V> unfiltered, Predicate<? super K> keyPredicate) {
    this.unfiltered = checkNotNull(unfiltered);
    this.keyPredicate = checkNotNull(keyPredicate);
  }

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

  @Override

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

  FilteredKeyMultimap(Multimap<K, V> unfiltered, Predicate<? super K> keyPredicate) {
    this.unfiltered = checkNotNull(unfiltered);
    this.keyPredicate = checkNotNull(keyPredicate);
  }

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

  @Override

    extends FilteredEntryMultimap<K, V> implements FilteredSetMultimap<K, V> {

  FilteredEntrySetMultimap(SetMultimap<K, V> unfiltered, Predicate<? super Entry<K, V>> predicate) {
    super(unfiltered, predicate);
  }

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

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

    extends FilteredKeyMultimap<K, V> implements FilteredSetMultimap<K, V> {

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

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

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

    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);
  }

    extends FilteredKeyMultimap<K, V> implements FilteredSetMultimap<K, V> {

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

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

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