forwarding.remove("c");
    assertEquals(immutableEntry("b", 2), forwarding.lastEntry());
  }

  @SuppressWarnings({"rawtypes", "unchecked"})
  public void testForwarding() {
    new ForwardingWrapperTester()
        .testForwarding(
            NavigableMap.class,
            new Function<NavigableMap, NavigableMap>() {
              @Override
              public NavigableMap apply(NavigableMap delegate) {