final OkHttpClient client = new OkHttpClient();
            MediaType MEDIA_TYPE_PNG;

            MultipartBody.Builder buildernew = new MultipartBody.Builder().setType(MultipartBody.FORM);
            for (Image image : media) {
                MEDIA_TYPE_PNG = image.getName().endsWith("png") ? MediaType.parse("image/png") : MediaType.parse("image/jpeg");
                RequestBody imageBody = RequestBody.create(MEDIA_TYPE_PNG, image.getPath());
                buildernew.addFormDataPart("file", image.getName(), imageBody);
            }
             MultipartBody requestBody = buildernew.build();
            final Request request = new Request.Builder()
                    .addHeader("authorization", "Bearer " + Credentials.getAuthToken(mContext))
                    .url(url)
                    .post(requestBody)
                    .build();
             Thread thread = new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        Response response = client.newCall(request).execute();
                        if (response.message().contentEquals("OK") && response.code() == 200) {
                            System.out.println(response.body().string());
                        }
                        System.out.println(response.body().string());
                    } catch (Exception e) {
                        Log.e(TAG, e.getMessage());
                    }
                }
            });
            thread.start();

{ "file" : [Files] }