I see that there is websocket endpoint which works out fins with Java tests. In logs I see
Connecting to: ws://127.0.0.1:8080/76f48a44-0af8-444c-ba97-3f1ed34af
For completeness, I'd like to add my own CLI tool: websocat.
$ websocat wss://echo.websocket.org/ qwer qwer 1234 1234
It does not do the "browser" part of the question, but should be a valid substitute for "curl" in this case.