code: public long getCooldownExpirationByTriggerAndMetric(Trigger trigger, Metric metric) {
      	String key = _hashTriggerAndMetric(trigger, metric);
  		return this.cooldownExpirationByTriggerAndMetric.containsKey(key) ? this.cooldownExpirationByTriggerAndMetric.get(key) : 0;
      }
docs: Returns the cool down expiration time of the notification given a metric,trigger combination.
  
  @param trigger   The trigger
  @param metric    The metric
  @return  cool down expiration time in milliseconds