public static function propertyIsValid($property_name, &$property_value, &$error)
 {
     if (!parent::propertyIsValid($property_name, $property_value, $error)) {
         return false;
     }
     if ($property_name === EVENT_TYPE_PARTY_LAUNCH_KEY_LAUNCH_ITEM_TITLE) {
         //	Item title is a string
         //
         if (!isset($property_value) || !is_string($property_value)) {
             $error = Error::withDomain(VALIDATION_ERROR_DOMAIN, VALIDATION_ERROR_CODE_INVALID_PROPERTY, $property_name . " should be a valid string.");
             return false;
         }
     }
     return true;
 }