add $notificationId to every broadcast notification

app/Events/EventParticipationCancelled.php

@@ -16,14 +16,16 @@ class EventParticipationCancelled implements ShouldBroadcastNow
 
     public $userId;
     public $event;
+    public $notificationId;
 
     /**
      * Create a new event instance.
      */
-    public function __construct($userId, Event $event)
+    public function __construct($userId, Event $event, $notificationId)
     {
         $this->userId = $userId;
         $this->event = $event;
+        $this->notificationId = $notificationId;
     }
 
     /**