}
public RequestSecurityTokenResponseType cancel(
RequestSecurityTokenType request, WebServiceContext context
) {
RequestParser requestParser = parseRequest(request, context);
KeyRequirements keyRequirements = requestParser.getKeyRequirements();
TokenRequirements tokenRequirements = requestParser.getTokenRequirements();
ReceivedToken cancelTarget = tokenRequirements.getCancelTarget();
if (cancelTarget == null || cancelTarget.getToken() == null) {
throw new STSException("No element presented for cancellation", STSException.INVALID_REQUEST);
}