@After
  public void cleanUp() throws Exception {
    HelixStoreOperator operator = new HelixStoreOperator(helixStore);
    if (operator.exist("/")) {
      operator.delete("/");
    }
    if (Files.exists(accountBackupDir)) {
      Utils.deleteFileOrDirectory(accountBackupDir.toFile());
    }
    router.close();
  }
cleanup after each test case.
@throws Exception Any unexpected exception.
ambry-account/src/test/java/com/github/ambry/account/RouterStoreTest.java