If it does support WebSockets then you can probably use it to test the server. You will need to implement some logic in the client for it to do anything meaningful.
Start simple. Get the server working and test it by opening multiple tabs in the browser.
I'm trying very simple connections to an "empty" b4j server.
To do it, initially I used an Android app, which created many wsh objects (connecting) but I got an exception for out of memory (about 220 connections).
So I changed and created a b4j client (thinking that my pc has more ram); this time I got some connection timeout exceptions (400 connections) and I'm not able to understand if the problem is the "client" or the server!