}

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

                (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})

    initMapWithNullKey();
    assertEquals(
        "put(present, value) should return the associated value",
        getValueForNullKey(),
        put(newEntry));

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

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEYS)
  public void testPut_nullKeyUnsupported() {