*/
public Document sign(ResponseType response, String idValueOfAssertion, KeyPair keypair, String referenceURI)
throws ParserConfigurationException, XPathException, TransformerFactoryConfigurationError, TransformerException,
GeneralSecurityException, MarshalException, XMLSignatureException {
SAML2Response saml2Response = new SAML2Response();
Document doc = saml2Response.convert(response);
doc.normalize();
Node theSibling = getNextSiblingOfIssuer(doc);
if (theSibling != null) {
this.sibling = theSibling;