I know this isn't part of the spec but supporting SocketAddress as a config property would be a really nice enhancement. Resource adapters often need to bind or connect to sockets. So you'll have to reimplement this every time and also which interfaces need to be bound. There is ususally support for this in the application server, but since it's not a "native" configuration property type you can't hook into it.
In the same vain supporting List properties would be nice, so that you can have a list of addresses to bind.