code: @VisibleForTesting
    synchronized void writeDelegationTokenToFile() throws IOException {
      if (this.fs.exists(this.tokenFilePath)) {
        LOGGER.info("Deleting existing token file " + this.tokenFilePath);
        this.fs.delete(this.tokenFilePath, false);
      }
  
      LOGGER.info("Writing new or renewed token to token file " + this.tokenFilePath);
      YarnHelixUtils.writeTokenToFile(this.token, this.tokenFilePath, this.fs.getConf());
      // Only grand access to the token file to the login user
      this.fs.setPermission(this.tokenFilePath, new FsPermission(FsAction.READ_WRITE, FsAction.NONE, FsAction.NONE));
    }
docs: Write the current delegation token to the token file.