multimap.put("foo", 1);

    assertEquals(
        "{foo=[3, -1, 2, null, 4, 1], null=[null, 0, -1], bar=[1, 2, null, 3]}",
        multimap.toString());
  }

  public void testPutMultimapOrdered() {
    Multimap<String, Integer> multimap = LinkedHashMultimap.create();
    multimap.putAll(initializeMultimap5());
    assertOrderingReadOnly(multimap);
  }

  public void testKeysToString_ordering() {