@Override
                        public FileVisitResult postVisitDirectory(final Path dir,
                                                                  final IOException exc) {
                            if (!dir.equals(path)) {
                                deleteIfExists(dir, success);
                            }
                            return super.postVisitDirectory(dir, exc);
                        }
@return True if path contains no files or directories.
@throws IOException if it is unable to list the contents of path
stroom-util/src/main/java/stroom/util/io/FileUtil.java