anchor.diff:  <1> Set a custom tag "source" to value "kafka".
   <2> All reported metrics will have `source=kafka` tag assigned in addition to the common tags described above.
   
  -====+====
  
positive.code: 
  Since one scheduler may have multiple executors, every executor metric has a `reactor_scheduler_id` tag.
  
  TIP: Grafana + Prometheus users can use https://raw.githubusercontent.com/reactor/reactor-monitoring-demo/master/dashboards/schedulers.json[a pre-built dashboard] which includes panels for threads, completed tasks, task queues and other handy metrics:
  
  == Publisher metrics
  Sometimes it is useful to be able to record metrics at some stage in your reactive pipeline.
  
negative.code: | reactor.flow.duration | Timer | Times the duration elapsed between a subscription and the termination or cancellation of the sequence. A status tag is added to specify what event caused the timer to end (`onComplete`, `onError`, `cancel`).
  |=======
  
  Want to know how many times your event processing has restarted due to some error? Read `reactor.subscribed`, because `retry()` operator will re-subscribe to the source publisher on error.
  
  Interested in "events per second" metric? Measure the rate of `reactor.onNext.delay` 's count.
  
  