protected function stickyChanged(Discussion $discussion, User $user, $isSticky)
 {
     $post = DiscussionStickiedPost::reply($discussion->id, $user->id, $isSticky);
     $post = $discussion->mergePost($post);
     if ($discussion->start_user_id !== $user->id) {
         $notification = new DiscussionStickiedBlueprint($post);
         $this->notifications->sync($notification, $post->exists ? [$discussion->startUser] : []);
     }
 }