/**
  * @inheritdoc
  */
 public function init()
 {
     if (!is_subclass_of($this->modelClass, IndexFormAbstract::className())) {
         throw new InvalidConfigException('Property "modelClass" must be implemented ' . IndexFormAbstract::className());
     }
     parent::init();
 }
 /**
  * @inheritdoc
  */
 public function init()
 {
     if ($this->formClass == null) {
         throw new InvalidConfigException('Property "formClass" must be contain form name with namespace.');
     }
     if (!is_subclass_of($this->formClass, RelationFormAbstract::className())) {
         throw new InvalidConfigException('Property "modelClass" must be implemented ' . RelationFormAbstract::className());
     }
     parent::init();
 }