@Override
  public void init() {
    super.init();
    clusterRequestsCounter = metricsRegistry.newCounter(CLUSTER_REQUESTS_NAME, "", 0L);
    clusterReadRequestsCounter = metricsRegistry.newCounter(CLUSTER_READ_REQUESTS_NAME, "", 0L);
    clusterWriteRequestsCounter = metricsRegistry.newCounter(CLUSTER_WRITE_REQUESTS_NAME, "", 0L);

    /*
     * NOTE: Please refer to HBASE-9774 and HBASE-14282. Based on these two issues, HBase is moving
     * away from using Hadoop's metric2 to having independent HBase specific Metrics. Use {@link
     * BaseSourceImpl#registry} to register the new metrics.
     */
    serverCrashMetrics = new OperationMetrics(registry, SERVER_CRASH_METRIC_PREFIX);
  }
Hadoop2 implementation of MetricsMasterSource. Implements BaseSource through BaseSourceImpl,
following the pattern
hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/master/MetricsMasterSourceImpl.java