code: public static Optional<List<Long>> getBytesListOptional(Config config, String path) {
          return Optional.ofNullable(getBytesList(config, path));
      }
docs: Get a configuration as list of sizes in bytes (parses special strings like "1Mb"). Return
  {@code null} if missing, wrong type or bad value.
  
  @param config
  @param path
  @return