static String getScope(Configuration conf, String clusterId, Object connectionObj) {
    return conf.get(METRICS_SCOPE_KEY,
      clusterId + "@" + Integer.toHexString(connectionObj.hashCode()));
  }
Returns the scope for a MetricsConnection based on the configured {@link #METRICS_SCOPE_KEY} or
by generating a default from the passed clusterId and connectionObj's hashCode.
@param conf          configuration for the connection
@param clusterId     clusterId for the connection
@param connectionObj either a Connection or AsyncConnectionImpl, the instance creating this
                     MetricsConnection.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/MetricsConnection.java