Cant create new launcer entry using jupyter-server-proxy

Just to check if you are placing this config in right file, this must go into jupyter_server_config.py that is placed in one of the config directories reported by jupyter --paths in your JupyterLab server.

Once the config is placed in right file, assuming your JupyterHub user is foo and you are using a unnamed default server, you must verify the new registered endpoint at https://myFQDN/hub/foo/test-server/.