docs: public synchronized void suspended(ServerActivityCallback requestCountListener) {
          this.paused = true;
          listenerUpdater.set(this, requestCountListener);
  
          if (activeRequestCountUpdater.get(this) == 0) {
              if (listenerUpdater.compareAndSet(this, requestCountListener, null)) {
                  requestCountListener.done();
              }
          }
      }