I am writting a Twitter web app by using Twitter4J on GAE/J.

I am saving Twitter and Request Token objects in session so that to be used after call back.

I have two servlets. IndexServlet sets session and HomeServlet get from session (hits on call back by twitter oAuth).

If I comment out session handling lines in both servlets then call backs works fine.

Please suggest any workaround. I am sharing my code here.

IndexServlet.java

 Twitter twitter = new Twitter();
               twitter.setOAuthConsumer("<masked>", "<masked>");
               RequestToken requestToken = null;
            try {
                    requestToken = twitter.getOAuthRequestToken();
                    log.info("OAuth token has been taken");
            } catch (TwitterException e) {
                    log.warning(e.toString());
            }

            HttpSession session = request.getSession();
            if (session.getAttribute("twitter")==null){
                    session.setAttribute("twitter", twitter);
                    out.println("-----------------------------> session is set");
            }

            if (session.getAttribute("token")==null){
                    session.setAttribute("token", requestToken);
                    out.println("-----------------------------> session is set");
            }
            String authUrl = requestToken.getAuthorizationURL();

HomeServlet.java

                       HttpSession session = request.getSession();

                    twitter = (Twitter)session.getAttribute("twitter");
                    r  = (RequestToken)session.getAttribute("token");

                    twitter.setOAuthAccessToken(r.getAccessToken());

                    twitter.updateStatus("Hello World!");

Exception

    javax.servlet.ServletException: java.lang.ArrayStoreException: [Ljava.lang.String;
 at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:239)
 at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
 at org.mortbay.jetty.Server.handle(Server.java:313)
 at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:506)
 at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:830)
 at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
 at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381)
 at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:139)
 at com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java:235)
 at com.google.apphosting.base.RuntimePb$EvaluationRuntime$6.handleBlockingRequest(RuntimePb.java:4950)
 at com.google.apphosting.base.RuntimePb$EvaluationRuntime$6.handleBlockingRequest(RuntimePb.java:4948)
 at com.google.net.rpc.impl.BlockingApplicationHandler.handleRequest(BlockingApplicationHandler.java:24)
 at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java:359)
 at com.google.net.rpc.impl.Server$2.run(Server.java:823)
 at com.google.tracing.LocalTraceSpanRunnable.run(LocalTraceSpanRunnable.java:56)