protected function toXml($xml, $rootElement)
 {
     parent::toXml($xml, $rootElement);
     $rootElement->appendChild($xml->createElement('barrier-level', $this->barrierLevel));
 }
 protected function toXml($xml, $rootElement)
 {
     parent::toXml($xml, $rootElement);
     $rootElement->appendChild($xml->createElement('participation-rate', $this->participationRate));
 }