@Override
  public void stop(String why) {
    if (this.stopped) {
      return;
    }
    if (this.connection != null) {
      try {
        this.connection.close();
      } catch (IOException ioe) {
        LOG.debug("Got " + ioe + " when closing connection");
      }
    }
    this.stopped = true;
  }
Implementation of a file cleaner that checks if an hfile is still referenced by backup before
deleting it from hfile archive directory.
hbase-backup/src/main/java/org/apache/hadoop/hbase/backup/BackupHFileCleaner.java