IssueTracker

The current Document API does not allow retention of directory uris.  For example:
Path:
/extSdCard/_documentTest
Uri:
content://com.android.externalstorage.documents/tree/0000-0000%3A/document/0000-0000%3A_documentTest

SingleDocumentFile doesn't support any write features, so we are left with TreeDocumentFile which is created with:

    public static DocumentFile fromTreeUri(Context context, Uri treeUri) {
        final int version = Build.VERSION.SDK_INT;
        if (version >= 21) {
            return new TreeDocumentFile(null, context,
                    DocumentsContractApi21.prepareTreeUri(treeUri));
        } else {
            return null;
        }
    }

However DocumentsContractApi21.prepareTreeUri(treeUri) truncates the document id returning a DocumentFile pointing to:

content://com.android.externalstorage.documents/tree/0000-0000%3A/document/0000-0000%3A

This is NOT the same URI!  It simply truncated this URI down to the tree root...

I cannot see a workaround without reflection into TreeDocumentFile.