GWT Cannot Serialize My Object from Hibernate

Here is the error I am receiving. I've looked everywhere for answers and I cannot figure out why anyone else isn't running into the same issue. The error happens when I'm retrieving a Proposal object from Hibernate which has a many-to-one constraint with User_Info on two properties, author and advisor. If needed I can provide the classes and hibernate configs. Just a note, I do implement isSerializeable and have empty constructors...I really appreciate any advice or help...

Starting Jetty on port 8888
   [WARN] Exception while dispatching incoming RPC call
com.google.gwt.user.client.rpc.SerializationException: java.lang.reflect.InvocationTargetException
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeWithCustomSerializer(ServerSerializationStreamWriter.java:760开发者_StackOverflow社区)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:723)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:612)
 at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:129)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:152)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:534)
 at com.google.gwt.user.server.rpc.RPC.encodeResponse(RPC.java:609)
 at com.google.gwt.user.server.rpc.RPC.encodeResponseForSuccess(RPC.java:467)
 at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:564)
 at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:188)
 at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:224)
 at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
 at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
 at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
 at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
 at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
 at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
 at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
 at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
 at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
 at org.mortbay.jetty.Server.handle(Server.java:324)
 at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
 at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843)
 at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
 at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
 at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
 at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396)
 at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)
Caused by: java.lang.reflect.InvocationTargetException
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:616)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeWithCustomSerializer(ServerSerializationStreamWriter.java:742)
 ... 30 more
**Caused by: com.google.gwt.user.client.rpc.SerializationException: Type 'edu.scranton.segpis.client.shared.User_Info_$$_javassist_2' was not included in the set of types which can be serialized by this SerializationPolicy or its Class object could not be loaded. For security purposes, this type will not be serialized.: instance = edu.scranton.segpis.client.shared.User_Info@1497d11**
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:610)
 at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:129)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:152)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:534)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeClass(ServerSerializationStreamWriter.java:700)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeImpl(ServerSerializationStreamWriter.java:730)
 at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:612)
 at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:129)
 at com.google.gwt.user.client.rpc.core.java.util.Collection_CustomFieldSerializerBase.serialize(Collection_CustomFieldSerializerBase.java:43)
 at com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSerializer.serialize(ArrayList_CustomFieldSerializer.java:36)
 ... 35 more
[ERROR] 500 - POST /uofsisweb/thesisproposal (127.0.0.1) 57 bytes
   Request headers
      Host: 127.0.0.1:8888
      User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.12) Gecko/20101027 Ubuntu/10.10 (maverick) Firefox/3.6.12
      Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
      Accept-Language: en-us,en;q=0.5
      Accept-Encoding: gzip,deflate
      Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
      Keep-Alive: 115
      Connection: keep-alive
      Cache-Control: no-cache
      Referer: 

      X-GWT-Permutation: HostedMode
     X-GWT-Module-Base: 

      Content-Type: text/x-gwt-rpc; charset=utf-8
      Content-Length: 185
      Pragma: no-cache
   Response headers
      Content-Type: text/plain

To manage this bug several options exists, you can see it here: http://code.google.com/intl/fr-FR/webtoolkit/articles/using_gwt_with_hibernate.html

The new GWT 2.1.0 release comes with RequestFactory which solves this bug with JPA (and so Hibernate).

Hibernate uses CGLIB to alter the objects it loads runtime, this is to enable lazy loading of object relations. Hibernate also uses internal lazy-loading collections (list, map), depending on mapping.

Both these things will make GWT choke. One way of making sure you get "clean" objects to GWT is to clone them by creating a brand new instance of your object and set all the values from the hibernate created one to your clean one.

Another is to make an reflection based object traversal that ensures there are no strange types lurking about.

In your case it seems to choke on something in User_Info:

edu.scranton.segpis.client.shared.User_Info_$$_javassist_2'

Perhaps you can isolate the offending field (mark one field after another as transient, just to see which one it is) - and then fix that one.