public void testTreeMultimapDerived() {
    TreeMultimap<DerivedComparable, DerivedComparable> multimap = TreeMultimap.create();
    assertEquals(ImmutableMultimap.of(), multimap);
    multimap.put(new DerivedComparable("foo"), new DerivedComparable("f"));
    multimap.put(new DerivedComparable("foo"), new DerivedComparable("o"));
    multimap.put(new DerivedComparable("foo"), new DerivedComparable("o"));

  public void testNewTreeMultisetDerived() {
    TreeMultiset<DerivedComparable> set = TreeMultiset.create();
    assertTrue(set.isEmpty());
    set.add(new DerivedComparable("foo"), 2);
    set.add(new DerivedComparable("bar"), 3);
    assertThat(set)
        .containsExactly(
            new DerivedComparable("bar"),
            new DerivedComparable("bar"),
            new DerivedComparable("bar"),
            new DerivedComparable("foo"),