WebSocket handshake error : Unexpected response code: 400

Question

I have to use engine.io-server-java in my project. When I initiate the eio function, The request has failed and thrown 400 Bad requests. How do I debug this problem? Are there any documents available for engine.io-server-java?

Error

WebSocket connection to 'ws://localhost:8080/engine.io/?EIO=3&transport=websocket&sid=Mg_ZSd5' failed: Error during WebSocket handshake: Unexpected response code: 400

Request Header

Code:

@WebServlet("/engine.io/*")
public class SocketIO extends HttpServlet {
    private final EngineIoServer server = new EngineIoServer();

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws IOException {
        server.handleRequest(request, response);
        server.on("connection", new Emitter.Listener() {
            @Override
            public void call(Object... arg0) {
                System.out.println("Socket connected");         
            }
        });
    }
}

Client Code:

var io = eio("http://localhost:8080", {transport: ["websocket"], upgrade: true, reconnection: false});