Android MyFiles - programmatically accessing common locations

Question

There are a number of questions relating to Intents and MyFiles app (the Samsung file manager).

What I'd like to do is programmatically drop files in a sensible place. For example, I want to export a CSV from a database application I have and I can use:

Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS)

but that just seems to end up pointing to a directory off the root of external storage

 ( /storage/emulated/0/Documents) 

which was empty and didn't exist as opposed to my healthy and enthusiastically filled MyFiles/Documents. whereas MyFiles has a built-in short cut to some Documents directory buried in some obscure place which I haven't located. So Samsung have kindly hidden the technical complexity of the file system but haven't left a clue as to where things really are for the poor old app designer.

Is there a way of programmatically identifying the location of the MyFiles\Documents directory and more generally the pre-programmed and user specified locations so that I can then place documents where the user expects to find them rather than scattered all over the place (which generally seems to be the case when you explore the mess that is in the external storage directory structure)?

                if (SpennyUtils.isExternalStorageWritable() && isStoragePermissionGranted(false)) {
                String temp = Environment.getExternalStoragePublicDirectory(
                        Environment.DIRECTORY_DOCUMENTS).getPath();
                Log.i(TAG, "Documents public dir: " + temp);
                createSubDirIfNotExists(temp);
                FileSaveDialog.Default_File_Name = "default.csv";
                Toast.makeText(RideListActivity.this, "Chosen FileOpenDialog File: " +
                        Environment.getExternalStoragePublicDirectory(
                                Environment.DIRECTORY_DOCUMENTS).getPath(), Toast.LENGTH_LONG).show();
                FileSaveDialog.chooseFile_or_Dir(Environment.getExternalStoragePublicDirectory(
                        Environment.DIRECTORY_DOCUMENTS).getPath());
            }