ImmutableMultimap<String, Object> outputMap =
        Multimaps.index(stringToObject.values(), Functions.toStringFunction());
    assertEquals(stringToObject, outputMap);
  }

  public void testIndexIterator() {
    Multimap<String, Object> stringToObject =
        new ImmutableMultimap.Builder<String, Object>()
            .put("1", 1)
            .put("1", 1L)
            .put("1", "1")
            .put("2", 2)