public void shutDownConnections() {
    this.heartbeatHandler.shutdown();
    this.rmProxyRelayer.shutdown();
  }
@Test(timeout = 10000)
  public void testShutDownConnections()
      throws YarnException, IOException, InterruptedException {
    launchUAM(attemptId);
    registerApplicationMaster(
        RegisterApplicationMasterRequest.newInstance(null, 0, null), attemptId);
    uam.shutDownConnections();
    while (uam.isHeartbeatThreadAlive()) {
      LOG.info("waiting for heartbeat thread to finish");
      Thread.sleep(100);
    }
  }