code: public void enqueue(SnackbarEvent event) {
          synchronized (this) {
              if (!eventsSet.contains(event)) {
                  eventsSet.add(event);
                  eventQueue.offer(event);
              } else if (currentEvent == event && pauseTransition != null) {
                  pauseTransition.playFromStart();
              }
          }
          if (processingQueue.compareAndSet(false, true)) {
              Platform.runLater(() -> {
                  currentEvent = eventQueue.poll();
                  if (currentEvent != null) {
                      show(currentEvent);
                  }
              });
          }
      }
docs: Shows {@link SnackbarEvent SnackbarEvents} one by one. The next event will be shown after the current event's duration.
  
  @param event the {@link SnackbarEvent event} to put in the queue.