(EDIT: The question - see also "How you can help" - would be if others can reproduce the bug, if it is known (Link.), what workarounds are recommended.)
Goal: Create a tiny temp file, then delete file with final filename, then rename temp to final. (Standard safesave-approach. You do use it, right.)
Problem: Fails after many test loop iterations. Files.move() throws FileAlreadyExistsException, tests instead using file.renameTo() return false sometimes. The file is indeed not renamed then. My tests …