@Override
    public void shutdown() throws InterruptedException {
      try {
        long startTime = System.currentTimeMillis();
        router.close();
        logger.info("Router shutdown took {} ms", System.currentTimeMillis() - startTime);
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
{@inheritDoc}
Request to clean up resources used by this helper class, i.e. NetworkClient in this context
ambry-tools/src/main/java/com/github/ambry/tools/admin/ConcurrencyTestTool.java