what would you expect to see as a succesful demonstration of Heavy URL protection working?
The idea is, that you use BaDOS - which is L7 DDoS protection based on Machine Learning. And a heavy URL would a URL which the ML should consider specially, because a request to this URL would cause a high load on the pool member(s) and an attacker could consume all resources on the backend system with just a few requests. See this URL: https://clouddocs.f5.com/training/community/ddos/html/class7/bados/module2.html
You would need a web application that has a similar URL, for example SELECT * FROM a large database. Then you try a low and slow attack on this URL and see how BaDOS recognizes and mitigates such attack.