In FileSystemutils.freeSpaceWindows(String path,long timeout) , path cannot be null. In this function for following assignment
path = FilenameUtils.normalize(path,bool), path is assigned null value when
(1) path argument is null.
(2) path argument is illegal/invalid path as per windows system.
For above test case, as path is illegal for windows system, Nullpointer exception occurs. A check for validity of path as per windows file system, will resolve this bug.