Vietnamese is really only a problem if you don't have good Unicode locale support
CEHJ, my decision is made:
in order to avoid endless looping in file-tree-walking (I call it tree-survey),
I had to write code to avoid symbolic links.
One of the methods involved is File.toPath().
This method throws InvalidPathException if characters outside ASCII (!..~) are detected.
Of course there will be a setting or a hack but I don't want to sail in deep water
as I don't have my company resources behind me any more.
I'm satisfied as it works a bit for me.
HAPPY XMAS and NEW YEAR!