code: @Override
    public synchronized void handleEvent(final Event event) {
      if (event.getType() == EventType.JOB_FINISHED && Status.FAILED
          .equals(event.getData().getStatus())) {
        this.value = this.value + 1;
      }
    }
docs: Listen for events to maintain correct value of number of failed jobs {@inheritDoc}
  
  @see azkaban.event.EventListener#handleEvent(azkaban.event.Event)