Why do I see duplicate association...

After importing a seam-gen project into JBoss Tools, you may have received the following error:

org.hibernate.console.HibernateConsoleRuntimeException: Persistence unit not found: 'null'.

You may be inclined to think that the reason this happens is because the persistence unit descriptor is named persistence-dev.xml rather than persistence.xml, like JBoss Tools expects. You are partially right in your thinking. However, you do not have to rename persistence-dev.xml to persistence.xml to get JBoss Tools to recognize it. The solution is even simpler.

After importing the seam-gen project into Eclipse, you should immediately right click on your project in the Project Explorer and select Refresh. This step gets Eclipse to recognize the output files from the Ant build that runs after the import. The Hibernate Console plug-in is then able to find the persistence unit configuration so you can open a session factory and start using it.

You still won't be able to use the JBoss Tools form editor to modify the persistence unit descriptor. This goes back to your first instinct. JBoss Tools expects the persistence unit descriptor to be named persistence.xml located in a META-INF folder that's on Eclipse's build path, rightly so. We are considering modifying seam-gen so that the configuration files for the dev profile have standard names and are on the build path. Then seam-gen can work its relocation magic when you are building for other profiles, which likely are not part of your daily development build cycle.