}

  /** Explicitly specifies the return type of this {@code Invokable}. */
  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<?, ?> invokable = type.method(method);
      if (!invokable.isPrivate()
          && !invokable.isSynthetic()
          && invokable.isStatic()
          && type.isSupertypeOf(invokable.getReturnType())) {
        @SuppressWarnings("unchecked") // guarded by isAssignableFrom()
        Invokable<?, ? extends T> factory = (Invokable<?, ? extends T>) invokable;
        factories.add(factory);

      Invokable<?, ?> invokable = type.method(method);
      if (!invokable.isPrivate()
          && !invokable.isSynthetic()
          && invokable.isStatic()
          && type.isSupertypeOf(invokable.getReturnType())) {
        @SuppressWarnings("unchecked") // guarded by isAssignableFrom()
        Invokable<?, ? extends T> factory = (Invokable<?, ? extends T>) invokable;
        factories.add(factory);

      calledWith(type, s);
    }

    void check() {
      runTester();
      TypeToken<?> defaultType = (TypeToken<?>) getDefaultParameterValue(0);
      assertTrue(new TypeToken<List<? super Number>>() {}.isSupertypeOf(defaultType));
    }
  }

  public void testGenericTypeTokenDefaultValue() {
    new GenericTypeTokenDefaultValueChecker().check();
  }