code: protected String getMetricName(Map<String, String> metadata, String eventName) {
      return JOINER.join(METRIC_KEY_PREFIX, metadata.get(METADATA_JOB_ID), metadata.get(METADATA_TASK_ID),
          EVENTS_QUALIFIER, eventName);
    }
docs: Constructs the metric key to be emitted.
  The actual event name is enriched with the current job and task id to be able to keep track of its origin
  
  @param metadata metadata of the actual {@link GobblinTrackingEvent}
  @param eventName name of the actual {@link GobblinTrackingEvent}
  @return prefix of the metric key