}

        final Class<?>[] interfaces = clazz.getInterfaces();
        final Type[] interfaceTypes = clazz.getGenericInterfaces();
        for (int i = 0; i < interfaces.length; ++i) {
            gatherTypeVariables(interfaces[i], interfaceTypes[i], map);
        }

        return map;
    }

    /**

    private final int identity = generateInt();
    private final Class<?> interfaceType;

    FreshInvocationHandler(Class<?> interfaceType) {
      this.interfaceType = interfaceType;
    }

    @Override
    protected @Nullable Object handleInvocation(
        Object proxy, Method method, @Nullable Object[] args) {
      return interfaceMethodCalled(interfaceType, method);
    }

    @Override
    public int hashCode() {

    private final int identity = generateInt();
    private final Class<?> interfaceType;

    FreshInvocationHandler(Class<?> interfaceType) {
      this.interfaceType = interfaceType;
    }

    @Override
    protected @Nullable Object handleInvocation(
        Object proxy, Method method, @Nullable Object[] args) {
      return interfaceMethodCalled(interfaceType, method);
    }

    @Override
    public int hashCode() {

        .testAllPublicInstanceMethods(new ForwardingWrapperTester());
  }

  private <T> void assertFailure(
      Class<T> interfaceType,
      Function<T, ? extends T> wrapperFunction,
      String... expectedMessages) {
    try {
      tester.testForwarding(interfaceType, wrapperFunction);
    } catch (AssertionFailedError expected) {
      for (String message : expectedMessages) {

        .testAllPublicInstanceMethods(new ForwardingWrapperTester());
  }

  private <T> void assertFailure(
      Class<T> interfaceType,
      Function<T, ? extends T> wrapperFunction,
      String... expectedMessages) {
    try {
      tester.testForwarding(interfaceType, wrapperFunction);
    } catch (AssertionFailedError expected) {
      for (String message : expectedMessages) {

    FreshValueGenerator generator =
        new FreshValueGenerator() {
          @Override
          @Nullable Object interfaceMethodCalled(Class<?> interfaceType, Method method) {
            return getDummyValue(TypeToken.of(interfaceType).method(method).getReturnType());
          }
        };
    for (Entry<Class<?>, Collection<Object>> entry : distinctValues.asMap().entrySet()) {

    FreshValueGenerator generator =
        new FreshValueGenerator() {
          @Override
          @Nullable Object interfaceMethodCalled(Class<?> interfaceType, Method method) {
            return getDummyValue(TypeToken.of(interfaceType).method(method).getReturnType());
          }
        };
    for (Entry<Class<?>, Collection<Object>> entry : distinctValues.asMap().entrySet()) {