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

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