assertEquals(2, factory.count);
    assertEquals(Sets.newHashSet(4, 3, 1), multimap.get(Color.BLUE));
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testNewSetMultimapSerialization() {
    CountingSupplier<Set<Integer>> factory = new SetSupplier();
    Map<Color, Collection<Integer>> map = new HashMap<>();
    SetMultimap<Color, Integer> multimap = Multimaps.newSetMultimap(map, factory);