private Set<String> getFilenameFromBulkLoad(Map<byte[], List<Path>>[] maps) {
    Set<String> filenames = new HashSet<>();
    for (Map<byte[], List<Path>> map : maps) {
      if (map == null) {
        continue;
      }

      for (List<Path> paths : map.values()) {
        for (Path p : paths) {
          filenames.add(p.getName());
        }
      }
    }
    return filenames;
  }
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