custom authentication provider

[Oliver Jones]

Hi, all.

I'm working on a custom authentication provider, following the example in
Chapter 18 of the manual.

I'm trying to authenticate using a one-time URL looking something like this:

     https://hostname/guacamole?sessionkey=HardToGuessValue

It seems, from the definition of the Credentials object, that I should be
able to use code like this:

       HttpServletRequest request = credentials.getRequest();
       String sessionkey = request.getParameter("sessionkey");

But, getParameter(), in this context, returns a null string.
 getParameterMap() returns an empty dictionary object.   I'm obviously
missing something. What's the right way to get URL parameters into a custom
authentication provider?

Thanks.