public static function loadRelation(ActiveRecord $model, $relationName, $data, $requiredData = [])
    {
        $relationClass = $model->getRelation($relationName)->modelClass;
        return static::loadMultiple(
            @$data[(new $relationClass())->formName()],
            $relationClass,
            $model->$relationName,
            $requiredData
        );
    }