code: private static <T, U> Promise<T> ofFailure(String message, List<Try<U>> failed) {
  		StacklessException exception = new StacklessException(RemoteFsClusterClient.class, message);
  		failed.stream()
  				.map(Try::getExceptionOrNull)
  				.filter(Objects::nonNull)
  				.forEach(exception::addSuppressed);
  		return Promise.ofException(exception);
  	}
docs: shortcut for creating single Exception from list of possibly failed tries