code: @Test public void testServerHeartbeat() throws Exception {
    URL serverURL=URL.valueOf("header://localhost:55555?transporter=netty3");
    serverURL=serverURL.addParameter(Constants.HEARTBEAT_KEY,1000);
    TestHeartbeatHandler handler=new TestHeartbeatHandler();
    server=Exchangers.bind(serverURL,handler);
    System.out.println("Server bind successfully");
    FakeChannelHandlers.setTestingChannelHandlers();
    serverURL=serverURL.removeParameter(Constants.HEARTBEAT_KEY);
    client=Exchangers.connect(serverURL);
    Thread.sleep(10000);
    Assert.assertTrue(handler.disconnectCount > 0);
    System.out.println("disconnect count " + handler.disconnectCount);
  }
  