client ip to maintain session affinity is to possible with mod_cluster, nor with standard mod_proxy balancers.
Additionally what will you do in case 2 client applications run on the same box?
Two client applications running on the same box would be routed to the same JBoss instance. Information in the web service payload distinguishes the unique clients and the server returns the appropriate data.
Having ip based sticky session in the http tier would add flexibility to a JBoss environment and solve this particular problem for IT shops which don't have control over the the architecture of third party software.
Would it be appropriate to request this feature for a future version of mod_cluster?
I think you miss something (or I miss something) HTTP doesn't define an header for the client IP, so the only the thing that the httpd (mod_cluster) in the socket address which could be a proxy. So what you want to do is not going to work in many cases.
I don't think the client ip could/will be use to handle the session affinity,