protected function prepareSecurityTokenRequest($username, $password, $address)
    {
        $fileName = __DIR__ . '/xml/SAML.xml';
        if (!file_exists($fileName)) {
            throw new \Exception("The file $fileName does not exist");
        }

        $template = file_get_contents($fileName);
        $template = str_replace('{username}', $username, $template);
        $template = str_replace('{password}', $password, $template);
        $template = str_replace('{address}', $address, $template);
        return $template;
    }