ImmutableMap<String, Integer> map = ImmutableMap.of();
    ImmutableSetMultimap<String, Integer> expected = ImmutableSetMultimap.of();
    assertEquals(expected, map.asMultimap());
  }

  public void testAsMultimapCaches() {
    ImmutableMap<String, Integer> map = ImmutableMap.of("one", 1);
    ImmutableSetMultimap<String, Integer> multimap1 = map.asMultimap();
    ImmutableSetMultimap<String, Integer> multimap2 = map.asMultimap();