/**
  * Sets restriction rules for fields.
  *
  * @since 1.0.0
  *
  * @param GP_Validation_Rules $rules The validation rules instance.
  */
 public function restrict_fields($rules)
 {
     $rules->project_id_should_not_be('empty');
     $rules->locale_slug_should_not_be('empty');
     $rules->user_id_should_not_be('empty');
     $rules->action_should_not_be('empty');
     $rules->set_slug_should_not_be('empty');
 }