That line gives you a URL like this:
http://host:port/context/www/gwtView.test/AssociationServlet
Go ahead and substitute your host/port/context and paste that into
your browser's address bar. You should get a message about GET not
being supported, as I recall. That's the URL that you need to hit from
your client-side JS.
What's not clear to me from your description is how you're deploying
and viewing your app. The only HTML file you show is under WEB-INF,
which your app server should be hiding (stuff under WEB-INF is not
served up to the public). If I assume that
IncidentAssociationView.html gets copied to www/gwtView.test/ upon
deployment, then
> String relativeUrl = GWT.getModuleBaseURL() + "/AssociationServlet";
produces
http://host:port/context/www/gwtView.test//AssociationServlet (note
the double slash is not hurting anything, but unnecessary)
And that should work. However, I suspect that your HTML file is not
ending up at http://host:port/context/www/gwtView.test/IncidentAssociationView.html.
Can you tell me where IncidentAssociationView.html is deployed?