Ошибка flush() [java]

Возникла проблема. Не получается передать JSON, так как происходит исключение java.io.IOException: closed

Ошибка:

2020-08-06 01:45:26.261 1340-1457/com.example.cargarage W/System.err: java.io.IOException: closed
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at com.android.okhttp.okio.RealBufferedSink$1.write(RealBufferedSink.java:196)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at java.io.FilterOutputStream.close(FilterOutputStream.java:158)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at com.example.cargarage.NewsActivity$AsyncRequest.doInBackground(NewsActivity.java:123)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at com.example.cargarage.NewsActivity$AsyncRequest.doInBackground(NewsActivity.java:86)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at android.os.AsyncTask$2.call(AsyncTask.java:333)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
2020-08-06 01:45:26.262 1340-1457/com.example.cargarage W/System.err:     at java.lang.Thread.run(Thread.java:764)

Код:

class AsyncRequest extends AsyncTask<String, Integer, String> {

    HttpURLConnection urlConnection;
    BufferedOutputStream bos;
    protected String doInBackground(String... arg) {

        try {
            URL url = new URL(GlobalVariable.server + "news");
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestProperty("Content-Type", "application/json");
            urlConnection.setRequestMethod("POST");
            urlConnection.setDoInput(true);
            urlConnection.setDoOutput(true);
            urlConnection.connect();

            JSONObject jo = new JSONObject();

            jo.put("User_id", GlobalVariable.ID);

            bos = new BufferedOutputStream(urlConnection.getOutputStream());
            bos.write(jo.toString().getBytes());

            String result = urlConnection.getResponseMessage();
            Log.d("", "server response: " + result); //проверить, что вернет сервер

        } catch (JSONException | IOException e) {
            e.printStackTrace();
        } finally {
            try {
                bos.flush(); //очищает поток output-a
                bos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            //urlConnection.disconnect();
        }
        return null;
    }
}