Major Description
FilenameUtils.normalize will accept broken file names as UNC path even if their hostname part doesn't match the syntax of a proper hostname. Using certain hostnames like "." this may lead to strange side effects.
Most likely the best fix will be to make getPrefixLength verify the hostname part of a suspected UNC path and return a value of NOT_FOUND if it is not a valid hostname - much like it does for triple slashes.
