@Override
  public void updateRegionStats(ServerName serverName, byte[] regionName, RegionLoadStats stats) {
    String name = serverName.getServerName() + "," + Bytes.toStringBinary(regionName);
    ConcurrentMap<byte[], RegionStats> rsStats = computeIfAbsent(serverStats, serverName,
      () -> new ConcurrentSkipListMap<>(Bytes.BYTES_COMPARATOR));
    RegionStats regionStats =
      computeIfAbsent(rsStats, regionName, () -> new RegionStats(this.registry, name));
    regionStats.update(stats);
  }
A container class for collecting details about the RPC call as it percolates.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/MetricsConnection.java