code: private static boolean isSupportedClass(Class<?> clazz) {
          return Observable.class.isAssignableFrom(clazz) ||
                 Maybe.class.isAssignableFrom(clazz) ||
                 Single.class.isAssignableFrom(clazz) ||
                 Completable.class.isAssignableFrom(clazz);
      }
docs: Returns {@code true} if the specified {@link Class} can be handled by the
  {@link ObservableResponseConverterFunction}.