public final <R1 extends R> Invokable<T, R1> returning(TypeToken<R1> returnType) {
    if (!returnType.isSupertypeOf(getReturnType())) {
      throw new IllegalArgumentException(
          "Invokable is known to return " + getReturnType() + ", not " + returnType);
    }
    @SuppressWarnings("unchecked") // guarded by previous check
    Invokable<T, R1> specialized = (Invokable<T, R1>) this;

    Invokable<?, Object> invokable = A.method("publicFinalMethod");
    assertFalse(invokable.isAbstract());
    assertFalse(invokable.isPrivate());
    assertTrue(invokable.isFinal());
    assertTrue(invokable.isPublic());
    assertTrue(invokable.isAnnotationPresent(Tested.class));
  }

  public void testNativeMethod() throws Exception {
    Invokable<?, Object> invokable = A.method("nativeMethod");

    Invokable<?, Object> invokable = A.method("publicFinalMethod");
    assertFalse(invokable.isAbstract());
    assertFalse(invokable.isPrivate());
    assertTrue(invokable.isFinal());
    assertTrue(invokable.isPublic());
    assertTrue(invokable.isAnnotationPresent(Tested.class));
  }

  public void testNativeMethod() throws Exception {
    Invokable<?, Object> invokable = A.method("nativeMethod");

    ImmutableList.Builder<Invokable<?, ?>> builder = ImmutableList.builder();
    for (Method method : cls.getDeclaredMethods()) {
      Invokable<?, ?> invokable = Invokable.from(method);
      invokable.setAccessible(true);
      if (invokable.isPublic() && invokable.isStatic() && !invokable.isSynthetic()) {
        builder.add(invokable);
      }
    }

    }

    @Override
    protected @Nullable Object handleInvocation(
        Object proxy, Method method, @Nullable Object[] args) {
      Invokable<?, ?> invokable = interfaceType.method(method);
      ImmutableList<Parameter> params = invokable.getParameters();
      for (int i = 0; i < args.length; i++) {
        Parameter param = params.get(i);
        if (!isNullable(param)) {
          checkNotNull(args[i]);

      @Override
      boolean isNullable(Invokable<?, ?> invokable) {
        return containsNullable(invokable.getAnnotations());
      }

      @Override
      boolean isNullable(Parameter param) {
        return containsNullable(param.getAnnotations());
      }
    };

    abstract boolean isNullable(Invokable<?, ?> invokable);

    abstract boolean isNullable(Parameter param);
  }

    if (isPrimitiveOrNullable(invokable.getParameters().get(paramIndex))) {
      return; // there's nothing to test
    }
    @Nullable Object[] params = buildParamList(invokable, paramIndex);
    try {
      @SuppressWarnings("unchecked") // We'll get a runtime exception if the type is wrong.
      Invokable<Object, ?> unsafe = (Invokable<Object, ?>) invokable;

      throws NoSuchMethodException {
    Method getMethod = List.class.getMethod("get", int.class);
    Invokable<T, String> invokable =
        new TypeToken<T>(getClass()) {}.method(getMethod).returning(String.class);
    assertEquals(TypeToken.of(String.class), invokable.getReturnType());
  }

  public <T extends List<String>> void testMethod_parameterTypes() throws NoSuchMethodException {

    this.annotatedType = annotatedType;
  }

  /** Returns the type of the parameter. */
  public TypeToken<?> getType() {
    return type;
  }

  /** Returns the {@link Invokable} that declares this parameter. */
  public Invokable<?, ?> getDeclaringInvokable() {
    return declaration;
  }

  @Override
  public boolean isAnnotationPresent(Class<? extends Annotation> annotationType) {

      throws NoSuchMethodException {
    Method getMethod = List.class.getMethod("get", int.class);
    Invokable<T, String> invokable =
        new TypeToken<T>(getClass()) {}.method(getMethod).returning(String.class);
    assertEquals(TypeToken.of(String.class), invokable.getReturnType());
  }

  public <T extends List<String>> void testMethod_parameterTypes() throws NoSuchMethodException {