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