.addEqualityGroup(
            withNull, getSubjectGenerator().create((Object[]) createArrayWithNullValue()))
        .testEquals();
  }

  @CollectionSize.Require(absent = ZERO)
  public void testNotEqualsEmpty() {
    new EqualsTester()
        .addEqualityGroup(multimap())
        .addEqualityGroup(getSubjectGenerator().create())
        .testEquals();
  }

  public void testHashCodeMatchesAsMap() {