// can reuse it.
  public static <E extends Enum<?> & Feature<?>> void assertGoodFeatureEnum(
      Class<E> featureEnumClass) {
    final Class<?>[] classes = featureEnumClass.getDeclaredClasses();
    for (Class<?> containedClass : classes) {
      if (containedClass.getSimpleName().equals("Require")) {
        if (containedClass.isAnnotation()) {
          assertGoodTesterAnnotation(asAnnotation(containedClass));

  // can reuse it.
  public static <E extends Enum<?> & Feature<?>> void assertGoodFeatureEnum(
      Class<E> featureEnumClass) {
    final Class<?>[] classes = featureEnumClass.getDeclaredClasses();
    for (Class<?> containedClass : classes) {
      if (containedClass.getSimpleName().equals("Require")) {
        if (containedClass.isAnnotation()) {
          assertGoodTesterAnnotation(asAnnotation(containedClass));

    // Ensure that the Finalizer class has no nested classes.
    // See https://github.com/google/guava/issues/1505
    assertEquals(Collections.emptyList(), Arrays.asList(Finalizer.class.getDeclaredClasses()));
  }