In the chapter 22.6.1. Configure mod_cluster in Apache HTTP Server is
a mention about mod_cluster modules

The mod_cluster modules are already included when installing JBoss Core Services Apache HTTP Server or using JBoss Web Server and are loaded by default. 

This is misleading as it was true up unlit now. New Jws 3.1.0 will not have Apache httpd inside and it is produced as separate product (Jboss Core Services). In short, new Jws 3.1.0 is not able to be used as balancer.
There should be at least note like

Apache httpd server is only distributed as part of JWS up to JWS-3.1.0