title: Changing Vaadin flow (14) basic configuration doesn't affect
body: <p>I'm using Vaadin Flow (14.1.18) and my question is a very bizarre behavior I've faced.
  I have added the following configs into my Spring Boot project's application.properties file.</p>
  
  <pre class="lang-java prettyprint-override"><code>// Expected behavior: Vaadin Client to send heartbeat to the server every second    
  vaadin.heartbeatInterval=1
  // Expected Behavior: Vaadin Server to close Idle sessions after 3 seconds (3 rounds of failed heart beats)
  vaadin.closeIdleSessions=true
  </code></pre>
  
  <p>I have checked these configs to be applied practically on runtime using below code</p>
  
  <pre class="lang-java prettyprint-override"><code>DeploymentConfiguration deployConf = VaadinSession.getCurrent().getConfiguration();
  int hbi =deployConf.getHeartbeatInterval();
  boolean killIdle = deployConf.isCloseIdleSessions();
  logger.info("Deployment Config &gt;&gt; KillIdleSessions : {} -- HeartBeatInterval : {}", killIdle, hbi);
  </code></pre>
  
  <p>And I get the following result which shows my configs got applied</p>
  
  <blockquote>
    <p>2020-03-05 23:16:01.015  INFO 19224 --- [nio-9200-exec-3]
    com.package.sandbox.MainView : Deployment Config >> KillIdleSessions :
    true -- HeartBeatInterval : 1</p>
  </blockquote>
  
  <p>But, the problem is, during the runtime, it seems Vaadin is ignoring all these configs, and despite I close the browser (UI instance won't be there anymore to send heartbeats) the session stays open indefinitely and never get closed (or destroyed, in Vaadin's perspective).</p>