if (subprotocols != null) {
String selectedSubprotocol = selectSubprotocol(subprotocols);
if (selectedSubprotocol == null) {
throw new WebSocketHandshakeException("Requested subprotocol(s) not supported: " + subprotocols);
} else {
res.addHeader(Names.SEC_WEBSOCKET_PROTOCOL, selectedSubprotocol);
setSelectedSubprotocol(selectedSubprotocol);
}
}
ChannelFuture future = channel.write(res);