@Override
        public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
          Files.delete(dir);
          return FileVisitResult.CONTINUE;
        }
Delete a directory recursively or delete a single file.
@param file the file or directory to delete.
@throws IOException if all files could not be deleted.
ambry-utils/src/main/java/com/github/ambry/utils/Utils.java