code: public Interval getQueueInterval(Queue<Event> queue, Event tailEvent) {
  		DateTime endTime = DateUtils.fromString(tailEvent.getTimestamp());
  		DateTime startTime = DateUtils.fromString(queue.peek().getTimestamp());
  
  		return new Interval((int)endTime.minus(startTime.getMillis()).getMillis(), "milliseconds");
  	}
docs: Determines the time between the {@link Event} at the head of the queue and the
  {@link Event} at the tail of the queue.
  
  @param queue a queue of {@link Event}s
  @param tailEvent the {@link Event} at the tail of the queue
  @return the duration of the queue as an {@link Interval}