ExpandingMap.java creates test files using File.createTempFile("exp", "tmp");.

It calls deleteOnExit() on them, however the files are still open and this
has no effect on Windows. (see product bugs 4171239, 4205562)

 $ pwd
/c/TEMP
 $ ls -l exp*tmp
-rwxrwxrwx 1 otto None 314874799 Apr 1 06:12 exp39413tmp
-rwxrwxrwx 1 otto None 314874799 Apr 2 05:16 exp63711tmp