protected int compareFiles(@NonNull File lhs, @NonNull File rhs) {
        if (lhs.isDirectory() && !rhs.isDirectory()) {
            return -1;
        } else if (rhs.isDirectory() && !lhs.isDirectory()) {
            return 1;
        } else {
            return lhs.getName().compareToIgnoreCase(rhs.getName());
        }
    }
Compare two files to determine their relative sort order. This follows the usual
comparison interface. Override to determine your own custom sort order.
<p/>
Default behaviour is to place directories before files, but sort them alphabetically
otherwise.

@param lhs File on the "left-hand side"
@param rhs File on the "right-hand side"
@return -1 if if lhs should be placed before rhs, 0 if they are equal,
and 1 if rhs should be placed before lhs
android/modules/module_filepicker/src/main/java/com/nononsenseapps/filepicker/FilePickerFragment.java