private static long getMaxSequenceId(FileStatus[] files) {
    long maxSeqId = -1L;
    for (FileStatus file : files) {
      String fileName = file.getPath().getName();
      try {
        maxSeqId = Math.max(maxSeqId, Long
          .parseLong(fileName.substring(0, fileName.length() - SEQUENCE_ID_FILE_SUFFIX_LENGTH)));
      } catch (NumberFormatException ex) {
        LOG.warn("Invalid SeqId File Name={}", fileName);
      }
    }
    return maxSeqId;
  }
Is the given file a region open sequence id file.
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/WALSplitUtil.java