docs: public void addListener(final FilteredManagerListener<ManagerEvent> listener)
      {
          synchronized (this.listeners)
          {
              this.listeners.addListener(listener);
              synchronized (this.globalEvents)
              {
                  Collection<Class< ? extends ManagerEvent>> expandEvents = expandEvents(listener.requiredEvents());
                  this.globalEvents.addAll(expandEvents);
              }
          }
          logger.debug("listener  added " + listener);
      }