Server does not send subprotocol.

Hello,

I want to implement a WebSocket connection with Sec-Websocket-Protocol present in the header. Currently, based on the examples provided by this repo, the server does not send a Sec-Websocket-Protocol back in the response header of the upgrade, even though I see in the tide Websocket Implementation the header shall be appended inside the upgrade function if Sec-Websocket-Protocol is present in the client header.

Greetings

Start with the WebSocket upgrade implementation referenced in the issue and run the repository's examples with a client that sends Sec-WebSocket-Protocol. Compare the upgrade response headers with the requested protocol. Done means the server response includes the negotiated subprotocol when the client supplies Sec-WebSocket-Protocol.

Written by the indexing model from the issue text.