protected M multimap() {
    return multimap;
  }

  /**
   * @return an array of the proper size with {@code null} as the key of the middle element.
   */
  protected Entry<K, V>[] createArrayWithNullKey() {
    Entry<K, V>[] array = createSamplesArray();
    int nullKeyLocation = getNullLocation();
    Entry<K, V> oldEntry = array[nullKeyLocation];
    array[nullKeyLocation] = Helpers.mapEntry(null, oldEntry.getValue());

    }
  }

  /** @return an array of the proper size with {@code null} as the key of the middle element. */
  protected Entry<K, V>[] createArrayWithNullKey() {
    Entry<K, V>[] array = createSamplesArray();
    int nullKeyLocation = getNullLocation();
    Entry<K, V> oldEntry = array[nullKeyLocation];
    array[nullKeyLocation] = entry(null, oldEntry.getValue());

  protected M multimap() {
    return multimap;
  }

  /**
   * @return an array of the proper size with {@code null} as the key of the middle element.
   */
  protected Entry<K, V>[] createArrayWithNullKey() {
    Entry<K, V>[] array = createSamplesArray();
    int nullKeyLocation = getNullLocation();
    Entry<K, V> oldEntry = array[nullKeyLocation];
    array[nullKeyLocation] = Helpers.mapEntry(null, oldEntry.getValue());

                (k, v) -> {
                  assertNull(k);
                  assertEquals(getValueForNullKey(), v);
                  return v3();
                }));

    Entry<K, V>[] expected = createArrayWithNullKey();
    expected[getNullLocation()] = entry(null, v3());
    expectContents(expected);
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_KEYS})

    }
  }

  /** @return an array of the proper size with {@code null} as the key of the middle element. */
  protected Entry<K, V>[] createArrayWithNullKey() {
    Entry<K, V>[] array = createSamplesArray();
    int nullKeyLocation = getNullLocation();
    Entry<K, V> oldEntry = array[nullKeyLocation];
    array[nullKeyLocation] = entry(null, oldEntry.getValue());

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNullKeySupported() {
    initMapWithNullKey();
    expectContents(createArrayWithNullKey());
  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNullKeyUnsupported() {
    try {
      initMapWithNullKey();

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNullKeySupported() {
    initMapWithNullKey();
    expectContents(createArrayWithNullKey());
  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNullKeyUnsupported() {
    try {
      initMapWithNullKey();

    Multimap<K, V> withNull = multimap();
    new EqualsTester()
        .addEqualityGroup(original)
        .addEqualityGroup(
            withNull, getSubjectGenerator().create((Object[]) createArrayWithNullKey()))
        .testEquals();
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_VALUES)
  public void testEqualsMultimapWithNullValue() {
    Multimap<K, V> original = multimap();

    Multimap<K, V> withNull = multimap();
    new EqualsTester()
        .addEqualityGroup(original)
        .addEqualityGroup(
            withNull, getSubjectGenerator().create((Object[]) createArrayWithNullKey()))
        .testEquals();
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_VALUES)
  public void testEqualsMultimapWithNullValue() {
    Multimap<K, V> original = multimap();

  }

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testForEach_nullKeys() {
    initMapWithNullKey();
    List<Entry<K, V>> expectedEntries = Arrays.asList(createArrayWithNullKey());
    List<Entry<K, V>> entries = new ArrayList<>();
    getMap().forEach((k, v) -> entries.add(entry(k, v)));
    Helpers.assertEqualIgnoringOrder(expectedEntries, entries);
  }