code: private void remove(PollController conn)
    {
      if (conn == null) {
        return;
      }
  
      if (_lifecycle.isDestroyed()) {
        return;
      }
  
      _activeCount.incrementAndGet();
  
      if (_activeCount.decrementAndGet() == 0 && _lifecycle.isDestroyed()) {
        destroy();
      }
    }
docs: Removes the connection from the selection.