Location of custom UI files under Jetty

I have installed Jitsi Meet on a clean Ubuntu 18.04 with its default jetty server. It works fine and now I’d like to create my custom UI with Jitsi Meei API library.

However, I discovered that in the directory /usr/share/jitsi-meet/ where standard UI are hosted only index.html is web available (accessible as https://myserver.com). Any file created in /usr/share/jitsi-meet/ or sub-directory is not shown in the browser.

It’s clear that the URL path is intended to be the room ID and I can’t just place my files under jetty web root, and access it so my question is where I should host my own UI files and what is proper directory layout for custom UI files and the rules to distinguish resource files and room id.