code: protected void init(VaadinRequest request) {
  
  
          RDFUnitDemoSession.init("http://" + getClientIpAddr(request));
  
          initLayout();
          setPollInterval(15000);
  
          mainTab.addTab(new IntroTab(), "Introduction");
          mainTab.addTab(new EndpointTestTab(), "Test RDF Data");
          mainTab.setSelectedTab(1);
  
          // When user exits (window close, loose session) stop background threads
          this.addDetachListener((DetachListener) event -> {
              RDFUnitDemoSession.getTestExecutor().cancel();
              RDFUnitDemoSession.getTestGeneratorExecutor().cancel();
          });
  
      }
docs: /*
  After UI class is created, init() is executed. You should build and wire
  up your user interface here.