return o1.length() - o2.length();
        }
      };

  /** Test a TreeMultiset with a comparator that can return 0 when comparing unequal values. */
  public void testDegenerateComparator() throws Exception {
    TreeMultiset<String> ms = TreeMultiset.create(DEGENERATE_COMPARATOR);

    ms.add("foo");
    ms.add("a");
    ms.add("bar");
    ms.add("b");
    ms.add("c");