assertEquals(newHashSet("google"), keySet.tailSet("yahoo"));
    assertEquals(newHashSet("tree"), keySet.subSet("ask", "yahoo"));
  }

  @GwtIncompatible // SerializableTester
  public void testExplicitComparatorSerialization() {
    TreeMultimap<@Nullable String, @Nullable Integer> multimap = createPopulate();
    TreeMultimap<@Nullable String, @Nullable Integer> copy =
        SerializableTester.reserializeAndAssert(multimap);

    assertEquals(Ordering.natural(), multimap.valueComparator());
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testExplicitComparatorSerialization() {
    TreeMultimap<String, Integer> multimap = createPopulate();
    TreeMultimap<String, Integer> copy = SerializableTester.reserializeAndAssert(multimap);