On Windows, if you give a directory name with space-chars at the end
(like "C:\foo\ ") to java.io.File then

isDirectory() will return true, but the list() method
will return null even if there are files in the directory:

This breaks the contract between isDirectory()
and list(), which is if isDirectory() returns true then
list() must not return null. This situation arises from
bug 4849568.