expectNullKeyMissingWhenNullKeysUnsupported("containsKey(null) should return false or throw");
  }

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nonNullWhenNullContained() {
    initMapWithNullKey();
    assertFalse("containsKey(notPresent) should return false", getMap().containsKey(k3()));
  }

  @MapFeature.Require(ALLOWS_NULL_KEYS)