Websockets example not working.

[nelavelli]

I tried to run this example in my machine, I am getting webscoket connection error. below is the error message.
Uncaught DOMException: Failed to execute 'send' on 'WebSocket': Still in CONNECTING state.
at HTMLTextAreaElement. (http://localhost:8080/file?name=websocket.html:26:20)

One more doubt is that, in Spring 4.x we were having
@MessageMapping("")
@sendto(""), are these got removed in Spring 5.0?