code: @VisibleForTesting
    Collection<Token<? extends TokenIdentifier>> readDelegationTokens(Path tokenFilePath) throws IOException {
      LOGGER.info("Reading updated token from token file: " + tokenFilePath);
      return YarnHelixUtils.readTokensFromFile(tokenFilePath, this.fs.getConf());
    }
docs: Read the {@link Token}s stored in the token file.