@SuppressWarnings("unchecked") // super interface type of T
    Class<? super T> interfaceType = (Class<? super T>) Iterables.getOnlyElement(interfaces);
    new ForwardingWrapperTester()
        .testForwarding(
            interfaceType,
            new Function<Object, T>() {
              @Override
              public T apply(Object delegate) {
                T mock = mock(forwarderClass, CALLS_REAL_METHODS);

    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) {