Yup you are correct, and I have enabled the option to create Java5 bytecode in the parent pom. <plugin> | <groupId>org.apache.maven.plugins</groupId> | <artifactId>maven-compiler-plugin</artifactId> | <configuration> | <!-- Java5 for portability - also Glassfish works only in Java5 for now --> | <source>1.5</source> | <target>1.5</target> | <maxmem>1024m</maxmem> | <optimize>true</optimize> | </configuration> | </plugin> It still seems to be at the moment that the problem is those uberjars of "all" dependencies. Having the same class in more than one jar annoys the classloaders (cos they are not the same class then). I could go through and create exclusions for all jars in those uberjars but then the final EAR for a production (or integration test) deployment would be without them as well. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4116883#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...