@Override
        public Object createWebSocket(ServletUpgradeRequest request,
                                      ServletUpgradeResponse response) {
            return handler;
        }
Creates a {@link WebSocketCreator} that uses the given handler class/instance for
the WebSocket connections.

@param handlerWrapper The wrapped handler to use to manage WebSocket connections.
@return The WebSocketCreator.
src/main/java/spark/embeddedserver/jetty/websocket/WebSocketCreatorFactory.java