code: public function onAfterInit($event)
      {
          if (isset(Yii::$app->collectors['widgets']) and !Yii::$app->collectors['widgets']->registerMultiple($this, $this->widgets())) {
              throw new Exception('Could not register widgets for ' . $this->systemId . '!');
          }
  
          return parent::onAfterInit($event);
      }
docs: [[@doctodo method_description:onAfterInit]].
  
  @param [[@doctodo param_type:event]] $event [[@doctodo param_description:event]]
  
  @throws Exception [[@doctodo exception_description:Exception]]
  @return [[@doctodo return_type:onAfterInit]] [[@doctodo return_description:onAfterInit]]