Refactor inefficient WebSocket handshake #31373

This HandshakeHelpers class is a relic of an outdated design. Can you try simplifying this code by merging this method into the UpgradeHandshake class?

You could remove these allocations and query the header collection directly:

aspnetcore/src/Middleware/WebSockets/src/WebSocketMiddleware.cs

Lines 121 to 128 in c925f99

	var headers = new List<KeyValuePair<string, string>>();
	foreach (string headerName in HandshakeHelpers.NeededHeaders)
	{
	foreach (var value in _context.Request.Headers.GetCommaSeparatedValues(headerName))
	{
	headers.Add(new KeyValuePair<string, string>(headerName, value));
	}
	}

NeededHeaders can also be removed.

#31311 (comment)