@Override
  public Optional<MasterObserver> getMasterObserver() {
    return Optional.of(this);
  }
An example coprocessor that collects some metrics to demonstrate the usage of exporting custom
metrics from the coprocessor.
<p>
These metrics will be available through the regular Hadoop metrics2 sinks (ganglia, opentsdb,
etc) as well as JMX output. You can view a snapshot of the metrics by going to the http web UI of
the master page, something like http://mymasterhost:16010/jmx
</p>
@see ExampleRegionObserverWithMetrics
hbase-examples/src/main/java/org/apache/hadoop/hbase/coprocessor/example/ExampleMasterObserverWithMetrics.java