default long getLastMajorCompactionTimestamp(byte[] regionName) {
    return getLiveServerMetrics().values().stream()
      .filter(s -> s.getRegionMetrics().containsKey(regionName)).findAny()
      .map(s -> s.getRegionMetrics().get(regionName).getLastMajorCompactionTimestamp()).orElse(0L);
  }
Returns the names of backup masters
hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterMetrics.java