public static long getMaxRegionSequenceId(FileSystem walFS, Path regionDir) throws IOException {
    return getMaxSequenceId(getSequenceIdFiles(walFS, regionDir));
  }
Get the max sequence id which is stored in the region directory. -1 if none.
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/WALSplitUtil.java