*
   * @since 16.0
   */
  public static <K0 extends Enum<K0>> MultimapBuilderWithKeys<K0> enumKeys(Class<K0> keyClass) {
    checkNotNull(keyClass);
    return new MultimapBuilderWithKeys<K0>() {
      @SuppressWarnings("unchecked")
      @Override
      <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
        // K must actually be K0, since enums are effectively final

   *
   * @since 16.0
   */
  public static <K0 extends Enum<K0>> MultimapBuilderWithKeys<K0> enumKeys(Class<K0> keyClass) {
    checkNotNull(keyClass);
    return new MultimapBuilderWithKeys<K0>() {
      @SuppressWarnings("unchecked")
      @Override
      <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
        // K must actually be K0, since enums are effectively final

  public void testGetNonEmpty() {
    Collection<V> result = multimap().get(k0());
    assertFalse(result.isEmpty());
    assertContentsAnyOrder(result, v0());
  }

  @CollectionSize.Require(SEVERAL)
  public void testGetMultiple() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k0(), v1()), mapEntry(k0(), v2()));
    assertGet(k0(), v0(), v1(), v2());
  }

  public void testGetAbsentKey() {
    assertGet(k4());

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testMultimapRemoveDeletesFirstOccurrence() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k0(), v1()), mapEntry(k0(), v0()));

    List<V> list = multimap().get(k0());
    multimap().remove(k0(), v0());
    assertContentsInOrder(list, v1(), v0());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)

    int size = multimap().size();
    List<V> oldValues = new ArrayList<>(multimap().get(k0()));
    List<V> values = asList(v0(), v3(), v0());
    assertEquals(oldValues, new ArrayList<V>(multimap().replaceValues(k0(), values)));
    assertEquals(size - oldValues.size() + multimap().get(k0()).size(), multimap().size());
    assertTrue(multimap().get(k0()).containsAll(values));
  }

  @CollectionSize.Require(absent = ZERO)

    getMap().put(k0(), v0());
    assertThrows(IllegalArgumentException.class, () -> getMap().put(k1(), v0()));
    // verify that the bimap is unchanged
    expectAdded(e0());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(ZERO)
  public void testPutPresentKeyDifferentValue() {
    getMap().put(k0(), v0());
    getMap().put(k0(), v1());

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testPropagatesRemoveToMultimap() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k0(), v3()), mapEntry(k0(), v2()));
    Collection<V> result = multimap().asMap().get(k0());
    assertTrue(result.remove(v0()));
    assertFalse(multimap().containsEntry(k0(), v0()));
    assertEquals(2, multimap().size());
  }

  @CollectionSize.Require(absent = ZERO)

  public void testGetNonEmpty() {
    Collection<V> result = multimap().get(k0());
    assertFalse(result.isEmpty());
    assertContentsAnyOrder(result, v0());
  }

  @CollectionSize.Require(SEVERAL)
  public void testGetMultiple() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k0(), v1()), mapEntry(k0(), v2()));
    assertGet(k0(), v0(), v1(), v2());
  }

  public void testGetAbsentKey() {
    assertGet(k4());

  public void testKeys() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k0(), v1()), mapEntry(k1(), v0()));
    Multiset<K> keys = multimap().keys();
    assertEquals(2, keys.count(k0()));
    assertEquals(1, keys.count(k1()));
    assertEquals(3, keys.size());
    assertContainsAllOf(keys, k0(), k1());
    assertContainsAllOf(
        keys.entrySet(), Multisets.immutableEntry(k0(), 2), Multisets.immutableEntry(k1(), 1));
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testMultimapRemoveDeletesFirstOccurrence() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k0(), v1()), mapEntry(k0(), v0()));

    List<V> list = multimap().get(k0());
    multimap().remove(k0(), v0());
    assertContentsInOrder(list, v1(), v0());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)