opts.transports = new String[] {WebSocket.NAME};
socket = client(opts);
socket.io().on(Manager.EVENT_TRANSPORT, new Emitter.Listener() {
@Override
public void call(Object... args) {
Transport transport = (Transport)args[0];
transport.on(Transport.EVENT_REQUEST_HEADERS, new Emitter.Listener() {
@Override
public void call(Object... args) {
@SuppressWarnings("unchecked")
Map<String, String> headers = (Map<String, String>)args[0];
headers.put("X-SocketIO", "hi");