Rewriting should fail when any paths are null.

     * {@code /after/foo/bar.txt}.

     */

    public static File rewriteAfterRename(File beforeDir, File afterDir, File file) {

        if (file == null) return null;

        if (file == null || beforeDir == null || afterDir == null) return null;

        if (contains(beforeDir, file)) {

            final String splice = file.getAbsolutePath().substring(

                    beforeDir.getAbsolutePath().length());