private static BadRequestException createSessionException(HttpRequest request) {
        return new BadRequestException("Session id in request is not a number, request was '" +
                request.getUri().toString() + "'");
    }
Gets session id (as a number) from request (v2). Input request must have a valid path.

@param request a request
@return a session id
configserver/src/main/java/com/yahoo/vespa/config/server/http/SessionHandler.java