Recommended project structure for scalable multimodule project

I'm working on application that has to communicate like Restful client with Endpoint1, Endpoint2,...EndpointN calling methods let's say getAaa and getBbb. Every Endpoint has same methods and return the same context information but using own parameter list for calls and returning own response object structure. Till now I worked on prototype having only webapp project and 1 Endpoint like separate package in web project and it was quite simple to call methods and consume response or exceptions. Now I need to add Endpoint2, then expand further and I stuck to project design questions - how to have flexible structure and how to have unified response from all Endpoints calling methods in my ejb. Please point me to the right direction how to design Maven project structure and how to wire calls from ejb to different Endpoint using different parameter list and how to unify different response and catch exceptions to MyObject or MyExObject?

P.S.: I have full control of Endpoint Restful client code