code: protected void queue(DtmfEventImpl evt) {
          if (queue.size() == size) {
              queue.poll();
          }
          queue.offer(evt);
          logger.info(String.format("(%s) Buffer size: %d", detectorImpl.getName(), queue.size()));
      }
docs: Queues specified event.
  
  @param evt the event to be queued.