introduced when switched to using ThingSession to set license

[WARN] dispatch: Exception while executing edu.illinois.ncsa.mmdb.web.client.dispatch.SetLicense: unable to convert object null to RDF
java.lang.IllegalArgumentException: unable to convert object null to RDF
at org.tupeloproject.rdf.ObjectVisitor.visit(ObjectVisitor.java:41)
at org.tupeloproject.rdf.ObjectResourceMapping.map(ObjectResourceMapping.java:186)
at org.tupeloproject.rdf.ObjectResourceMapping.resource(ObjectResourceMapping.java:206)
at org.tupeloproject.kernel.Thing.map(Thing.java:257)
at org.tupeloproject.kernel.Thing.setValue(Thing.java:315)
at edu.illinois.ncsa.mmdb.web.server.dispatch.SetLicenseHandler.execute(SetLicenseHandler.java:101)
at edu.illinois.ncsa.mmdb.web.server.dispatch.SetLicenseHandler.execute(SetLicenseHandler.java:1)
at net.customware.gwt.dispatch.server.DefaultDispatch.doExecute(DefaultDispatch.java:78)
at net.customware.gwt.dispatch.server.DefaultDispatch.execute(DefaultDispatch.java:68)
at net.customware.gwt.dispatch.server.service.DispatchServiceServlet.execute(DispatchServiceServlet.java:24)
at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:562)
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 edu.illinois.ncsa.mmdb.web.server.MyDispatchServiceServlet.service(MyDispatchServiceServlet.java:72)
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$RequestHandler.content(HttpConnection.java:843)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)