This error is most likely caused by duplicate classpath resources. You can read more about classloading in WF at: Implicit module dependencies for deployments - WildFly 8 - Project Documentation Editor andClass Loading in WildFly - WildFly 8 - Project Documentation Editor
FYI, I changed my approach:
- I packaged all my ModeShape API calls in a separate .war application and offered all operations via REST. I'm using ModeShape 3.8.1, so I had to add the POST file upload functionality by myself.
- Finally, I only setup REST calls on client side to use Modeshape more modular.