MediaScannerConnection.scanFile not show files on Nexus 5

Question

I'm creating an application and i need to create and show to the user some folders. For testing i'm using my nexus 5 (android marshmallow). I'm using this code:

File imageRoot = new File(getFilesDir(), "MyDir");
            imageRoot.mkdir();

and after:

MediaScannerConnection.scanFile(MainActivity.this, new String[] imageRoot.toString()}, null, new MediaScannerConnection.OnScanCompletedListener() {
                @Override
                public void onScanCompleted(String path, Uri uri) {
                    Log.d("path","path is" + path);
                }
            });

In this case mkdir return true, but MediaScannerConnection doesn't show me files (or folder)in the internal storage.

Log.d show this path:

/data/user/0/com.example.federico.savefolder/files/MyDir/

but i don't see anything when i search in the folders.

I insert the permissions:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

I try this solution and creating a folder in the ExternalStorageDirectory (the path should be: "/storage/emulated/0") but doesn't work.

Any Solutions? thanks in advance.