public function toXMLString()
{
$str = '';
$str .= '<ns:MassPayReq>';
if ($this->MassPayRequest != null) {
$str .= '<ns:MassPayRequest>';
$str .= $this->MassPayRequest->toXMLString();
$str .= '</ns:MassPayRequest>';
}
$str .= '</ns:MassPayReq>';
return $str;
}
