docs: public static <U, V> Function<U, V> retryable(Function<U, V> base,
                                                  Class<? extends Throwable> exceptionClass,
                                                  int maxRetries,
                                                  int maxDelayBetweenRetries) {
      return new RetryingFunction<>(base, exceptionClass, maxRetries, maxDelayBetweenRetries);
    }