I haven't tried it but I guess you could use an ExceptionHandler on the server-side to construct the ServerFailure the way you want.
For authentication purpose however, unless you do login through RF too, I'd suggest using the following approach instead: https://groups.google.com/d/msg/google-web-toolkit/QeTpbPREaTE/ltyMAN3wThcJ -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
