public static void main(String[] args) throws IOException, MalformedObjectNameException {
    String str = dumpMetrics();
    System.out.println(str);
  }
Dump out a subset of regionserver mbeans only, not all of them, as json on System.out.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/DumpRegionServerMetrics.java