private function getAuthHeader()
    {
        $credential = $this->apiContext->getCredential();

        $header = '<wsse:Security SOAP-ENV:mustUnderstand="1" xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd">';
        $header .= '<wsse:UsernameToken wsu:Id="UsernameToken-9" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">';
        $header .= '<wsse:Username>' . $credential->getUsername() . '</wsse:Username>';
        $header .= '<wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">' . $credential->getPassword() . '</wsse:Password>';
        $header .= '</wsse:UsernameToken>';
        $header .= '</wsse:Security>';

        $headerbody = new \SoapVar($header, XSD_ANYXML, null, null, null);
        return new \SOAPHeader(self::PAYU_NAMESPACE, 'Security', $headerbody, true);
    }