docs: synchronized void fireEvent(final Event<?> event) {
          final String eventType = event.getType();
          List<Event<?>> events = synchronizedEvents.get(eventType);
          if (null == events) {
              events = new ArrayList<>();
              synchronizedEvents.put(eventType, events);
          }
  
          events.add(event);
          setChanged();
          notifyListeners(event);
      }