Save and delete image file using parse on heroku and mongoDB - mongodb

Question

I used heroku with mongoDB for using parse. I deployed parse-server-example and followed all of migration guide.
I want to save PNG file and delete it.
There are some problems T_T
When i save image file and seeing on mongoDB, file name is different from i want to save.
When i delete it using parse code on Android, fs.chunks and fs.files are left.
For 1st problem code is below
Java : Saving image file
Drawable drawable = getResources().getDrawable(R.drawable.ic_loading);
Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] img_write = stream.toByteArray();
ParseFile parseFile = new ParseFile("test.png", img_write);
testObject = new ParseObject("TestObject");
testObject.put("test", parseFile);
testObject.saveInBackground(new SaveCallback() {
#Override
public void done(ParseException e) {
if (e == null) {
Log.e("Write", "SUCCESS");
} else {
Log.e("Write", e.getMessage());
}
}
});
but when i retrieve image it's value of 'test(key)' is '32de5cf8c1b205a8e26367dae3b07ca3_test.png' though i made ParseFile's name for "test.png" and saved it to 'test(key)'.
For 2nd problem code is below
query = ParseQuery.getQuery("TestObject");
query.whereContains("test", "test.png");
query.findInBackground(new FindCallback<ParseObject>() {
#Override
public void done(List<ParseObject> objects, ParseException e) {
if (e == null) {
objectId = objects.get(0).getObjectId();
query.getInBackground(objectId, new GetCallback<ParseObject>() {
#Override
public void done(ParseObject object, ParseException e) {
if (e == null) {
object.deleteInBackground(new DeleteCallback() {
#Override
public void done(ParseException e) {
if (e == null) {
Log.e("Delete", "SUCCESS");
} else {
Log.e("Delete", e.getMessage());
}
}
});
} else {
Log.e("getInBackground", e.getMessage());
}
}
});
} else {
Log.e("findInBackground", e.getMessage());
}
}
});
I used 'whereContains' because it's name is '32de5cf8c1b205a8e26367dae3b07ca3_test.png'. And when i delete it 'TestObject' be null but 'fs.files' and 'fs.chunks' are left. I know it is kind of grid file. But is it right that when i delete it, grid files are left?
Please help me for my problems...Thank you for reading my questions.