* @throws GeneralSecurityException
*/
public Document sign(RequestAbstractType request, KeyPair keypair) throws SAXException, IOException,
ParserConfigurationException, GeneralSecurityException, MarshalException, XMLSignatureException {
SAML2Request saml2Request = new SAML2Request();
Document doc = saml2Request.convert(request);
doc.normalize();
Node theSibling = getNextSiblingOfIssuer(doc);
if (theSibling != null) {
this.sibling = theSibling;