/**
  * Register the addon events.
  *
  * @param AddonServiceProvider $provider
  */
 protected function registerEvents(AddonServiceProvider $provider)
 {
     if (!($listen = $provider->getListeners())) {
         return;
     }
     foreach ($listen as $event => $listeners) {
         foreach ($listeners as $key => $listener) {
             if (is_integer($listener)) {
                 $listener = $key;
                 $priority = $listener;
             } else {
                 $priority = 0;
             }
             $this->events->listen($event, $listener, $priority);
         }
     }
 }