[LayaAir3]HttpRequest自定义了headers，就会报跨域的问题，是设置的方式不对吗？

let xhr = new Laya.HttpRequest();

xhr.http.withCredentials = true;  // 确保请求带上 cookie

// xhr.once(Laya.Event.COMPLETE, this, onRequestComplete);

// xhr.once(Laya.Event.ERROR, this, onRequestError);

let headers = [

    "user_id", "1"

];

xhr.send(url, null, "get", "json", headers);

如果去掉headers，就是一个正常的请求，只是404，因为没有自定义headers

let xhr = new Laya.HttpRequest();

        xhr.http.withCredentials = true;  // 确保请求带上 cookie

        // xhr.once(Laya.Event.COMPLETE, this, onRequestComplete);

        // xhr.once(Laya.Event.ERROR, this, onRequestError);

        xhr.http.setRequestHeader("client", "3");

        xhr.send(url, null, "get", "json");

如果这样设置，就会报Failed to execute 'setRequestHeader' on 'XMLHttpRequest': The object's state must be OPENED.
 
该怎么自定义一些请求头参数呢？？？