http post method not sending json object to web server

I am trying to send json encoded string(params[0]) to the webserver with some header content using asyncTask. In the web server i am receiving headers but not receiving json encoded string and getting request code 200. Here is my BackgroundTask class:

@Override
protected String doInBackground(String... params) {
    try {

        URL url=new URL(jsonurl);
        HttpURLConnection httpURLConnection= (HttpURLConnection) url.openConnection();
        httpURLConnection.setRequestMethod("POST");
        httpURLConnection.setRequestProperty("Content-Length",
                Integer.toString(params[0].getBytes().length));
        httpURLConnection.setRequestProperty("Accept", "application/json");
        httpURLConnection.setRequestProperty("Content-Type", "application/json");
        httpURLConnection.setDoOutput(true);
        ResponseCode=httpURLConnection.getResponseCode();
        OutputStream OS=httpURLConnection.getOutputStream();
        BufferedWriter bufferedWriter=new BufferedWriter(new OutputStreamWriter(OS,"UTF-8"));
        String data= URLEncoder.encode(params[0], "UTF-8");


        bufferedWriter.write(data);

        bufferedWriter.flush();
        bufferedWriter.close();
        OS.close();
        InputStream IS=httpURLConnection.getInputStream();


        return "data saved";
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return "not saved into server";
}

and here is call to the BackgroundTask:

BackgroundTask backgroundTask= new BackgroundTask(this);
            JSONObject jsonObject=new JSONObject();
            JSONArray jsonArray=new JSONArray();
            try {

                jsonObject.put("mail",Email );
                jsonObject.put("name", Name);
                jsonObject.put("surname", Surname);
                jsonObject.put("password",Password);


            } catch (JSONException e) {
                e.printStackTrace();
            }

            jsonArray.put(jsonObject.toString());
            backgroundTask.execute(jsonObject.toString());