IllegalAccessError: org.jboss.security.SecurityActions in JBoss EAP 6 when packaging EAP 5 client jars to invoke EJB in EAP 5

Issue

• I've ported an application to JBoss EAP 6 and it needs to communicate with an application on JBoss 5 via RMI. I get the following exception when running it on JBoss EAP 6. We use many JBoss 4/5 jar files in this app (as mentioned in the stacktrace).

ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/ProcessEngine].[pe]] (http--127.0.0.1-8080-1) Servlet.service() for servlet pe threw exception: java.lang.IllegalAccessError: tried to access class org.jboss.security.SecurityActions from class org.jboss.security.SecurityAssociation
    at org.jboss.security.SecurityAssociation.<clinit>(SecurityAssociation.java:143) [jbosssx-client.jar:2.0.2.SP6]
    at org.jboss.ejb3.security.client.SecurityActions$PrincipalInfoAction$2.getPrincipal(SecurityActions.java:160) [jboss-ejb3-security-client.jar:5.0.1.GA (build: SVNTag=JBoss_5_0_1_GA date=200902231221)]
    at org.jboss.ejb3.security.client.SecurityActions.getPrincipal(SecurityActions.java:359) [jboss-ejb3-security-client.jar:5.0.1.GA (build: SVNTag=JBoss_5_0_1_GA date=200902231221)]
    at org.jboss.ejb3.security.client.SecurityClientInterceptor.invoke(SecurityClientInterceptor.java:49) [jboss-ejb3-security-client.jar:5.0.1.GA (build: SVNTag=JBoss_5_0_1_GA date=200902231221)]
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:102) [jboss-aop-client.jar:2.0.1.GA]
    at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:74) [jboss-ejb3-core-client.jar:5.0.1.GA (build: SVNTag=JBoss_5_0_1_GA date=200902231221)]
    at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:102) [jboss-aop-client.jar:2.0.1.GA]
    at org.jboss.aspects.remoting.PojiProxy.invoke(PojiProxy.java:62) [jboss-aspect-jdk50-client.jar:jboss-aspect-library-1.3]
    at $Proxy56.invoke(Unknown Source)  at org.jboss.ejb3.proxy.handler.ProxyInvocationHandlerBase.invoke(ProxyInvocationHandlerBase.java:261) [jboss-ejb3-proxy-client.jar:5.0.1.GA (build: SVNTag=JBoss_5_0_1_GA date=200902231221)]
    at org.jboss.ejb3.proxy.handler.session.SessionSpecProxyInvocationHandlerBase.invoke(SessionSpecProxyInvocationHandlerBase.java:101) [jboss-ejb3-proxy-client.jar:5.0.1.GA (build: SVNTag=JBoss_5_0_1_GA date=200902231221)]

• We created a eap5-client module in JBoss EAP 6, so that our application which calls JBoss EAP 5 can call it, but now we are getting a class cast exception when trying to connect:

...
Caused by: java.lang.ClassCastException: org.jboss.security.plugins.JBossSecurityContext cannot be cast to org.jboss.security.SecurityContext
    at org.jboss.security.SecurityContextFactory.createSecurityContext(SecurityContextFactory.java:117)
    at org.jboss.security.SecurityContextFactory.createSecurityContext(SecurityContextFactory.java:76)
    at org.jboss.security.SecurityContextFactory.createSecurityContext(SecurityContextFactory.java:133)
    at org.jboss.security.SecurityAssociationActions$SetPrincipalInfoAction.run(SecurityAssociationActions.java:65)
    ... 73 more