private FixedFileTrailer readTrailer(Path trailerPath) throws IOException {
    FSDataInputStream fsdis = fs.open(trailerPath);
    FixedFileTrailer trailerRead =
      FixedFileTrailer.readFromStream(fsdis, fs.getFileStatus(trailerPath).getLen());
    fsdis.close();
    return trailerRead;
  }
The number of used fields by version. Indexed by version minus two. Min version that we support
is V2
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/TestFixedFileTrailer.java