I ran into this problem. For me, I was just using Eclipse with Google App Engine (GAE) and GWT 2.8.1.
GAE was bringing in an old HttpServletResponse, which didn't have the required methods. The solution was to go to my project properties -> Java Build Path -> Order and Export. Then move the GWT SDK above the App Engine SDK. -- You received this message because you are subscribed to the Google Groups "GWT Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/google-web-toolkit. For more options, visit https://groups.google.com/d/optout.
