testers.add(SetCreationTester.class);
    testers.add(SetHashCodeTester.class);
    testers.add(SetEqualsTester.class);
    testers.add(SetRemoveTester.class);
    // SetRemoveAllTester doesn't exist because, Sets not permitting
    // duplicate elements, there are no tests for Set.removeAll() that aren't
    // covered by CollectionRemoveAllTester.
    return testers;
  }

  @Override

    testers.add(SetCreationTester.class);
    testers.add(SetHashCodeTester.class);
    testers.add(SetEqualsTester.class);
    testers.add(SetRemoveTester.class);
    // SetRemoveAllTester doesn't exist because, Sets not permitting
    // duplicate elements, there are no tests for Set.removeAll() that aren't
    // covered by CollectionRemoveAllTester.
    return testers;
  }

  @Override