public void testToStringWithNullKey() {
    initMultimapWithNullKey();
    testToStringMatchesAsMap();
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(absent = NON_STANDARD_TOSTRING)
  @MapFeature.Require(ALLOWS_NULL_VALUES)
  public void testToStringWithNullValue() {
    initMultimapWithNullValue();
    testToStringMatchesAsMap();
  }

  @CollectionFeature.Require(absent = NON_STANDARD_TOSTRING)