}

  public void testCopyOfDuplicateInconsistentWithEquals() {
    IntegerDiv10 three = new IntegerDiv10(3);
    IntegerDiv10 eleven = new IntegerDiv10(11);
    IntegerDiv10 twelve = new IntegerDiv10(12);
    IntegerDiv10 twenty = new IntegerDiv10(20);

    List<IntegerDiv10> original = ImmutableList.of(three, eleven, twelve, twenty);

    Multiset<IntegerDiv10> copy = ImmutableSortedMultiset.copyOf(original);