We use the org.jboss.weld.environment.servlet.Listener to enable our servlet application to use weld.
On user logout we invalidate the session and redirect the user away.
It seems like tomcat is firing a requestDestroyed when we do that (that is, after we invalidate the session)

The weld code then produces this stack trace:

java.lang.IllegalStateException: getAttribute: Session already invalidated
at org.apache.catalina.session.StandardSession.getAttribute(StandardSession.java:1167)
at org.apache.catalina.session.StandardSessionFacade.getAttribute(StandardSessionFacade.java:122)
at org.jboss.weld.context.http.HttpConversationContextImpl.getSessionAttribute(HttpConversationContextImpl.java:29)
at org.jboss.weld.context.http.HttpConversationContextImpl.getSessionAttribute(HttpConversationContextImpl.java:13)
at org.jboss.weld.context.AbstractConversationContext.copyConversationIdGeneratorAndConversationsToSession(AbstractConversationContext.java:177)
at org.jboss.weld.context.AbstractConversationContext.dissociate(AbstractConversationContext.java:161)
at org.jboss.weld.servlet.ConversationContextActivator.disassociateConversationContext(ConversationContextActivator.java:171)
at org.jboss.weld.servlet.HttpContextLifecycle.requestDestroyed(HttpContextLifecycle.java:236)
at org.jboss.weld.servlet.WeldInitialListener.requestDestroyed(WeldInitialListener.java:118)
at org.jboss.weld.servlet.api.helpers.ForwardingServletListener.requestDestroyed(ForwardingServletListener.java:38)
at org.apache.catalina.core.StandardContext.fireRequestDestroyEvent(StandardContext.java:6137)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:207)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)

I feel that somehow copyConversationIdGeneratorAndConversationsToSession should check if the session is valid.
On the other hand, I wonder if that conversation context dance need to be done at all. We are not using this scope.