The jersey project (jersey.dev.java.net) provides support for building REST endpoints and their clients.
The functionality of AbstractHubServlet and AbstractSubServlet can be replaced with equivalent classes annotated with jax-rs annotations.
The advantage of this would be that the resulting classes may be implemented in a servlet container or an embedded container like Grizzly2.
This allows much flexibility in writing unit tests that can start a server and a client and then make client issue requests to the server.
Note that I already have implementation for these classes that have been tested already.
This is not a MUST need right now but I am adding this to keep track of the idea.