/**
  * The ProfilableEventManager constructor.
  *
  * @param Stopwatch $stopwatch Optional; can be set later
  */
 public function __construct(Stopwatch $stopwatch = null)
 {
     parent::__construct();
     if (!$stopwatch) {
         $stopwatch = new NullStopwatch();
     }
     $this->stopwatch = $stopwatch;
 }