HttpServerRequest#toNetSocket make the server report its WebSocket capabilities #5600
Description
Initial report in eclipse-vertx/vertx-http-proxy#125
HttpServerRequest#toNetSocket can be used in a proxy to manually upgrade a server connection to WebSocket.
When this method is called, Netty's WebSocketServerExtensionHandler adds to response headers all the capabilities of the server (e.g. per message compression). This is fine when the origin (backend) has the same configuration. Otherwise, this breaks the WebSocket handshake protocol.