title: How to return to the main page after making a payment on PayBox, with VAADIN?
body: <p>I would like to return to my main page after making a payment.
  I have a return parameter in my url that is zero until I went to the payment site and I did not validate my payment.
  After payment, therefore non-zero return parameter (ex:  <a href="http://localhost:8080/app0/#!retour?retour=APP:337:2:/QSYS.LIB/CMT31.LIB/PAMWTRCL8.PGM&amp;mt=3000&amp;code=00000&amp;key=krE0CVCuH%2FQ1fw2iOEIt6xYVqdmcUjiUNg2n9oSHcL2UkaE7N5WyzargWQS85u7IKNH6m38zuN3qXcx42KqEfXIiem1MHyfdQdamqzKfCP25Jwze7PPhGBjXSzO4JkKi2Pp2w573XKAwBFMkuaLcBeFb3Uq1qvWyRumYdk89Sro%3D" rel="nofollow noreferrer">http://localhost:8080/app0/#!retour?retour=APP:337:2:/QSYS.LIB/CMT31.LIB/PAMWTRCL8.PGM&amp;mt=3000&amp;code=00000&amp;key=krE0CVCuH%2FQ1fw2iOEIt6xYVqdmcUjiUNg2n9oSHcL2UkaE7N5WyzargWQS85u7IKNH6m38zuN3qXcx42KqEfXIiem1MHyfdQdamqzKfCP25Jwze7PPhGBjXSzO4JkKi2Pp2w573XKAwBFMkuaLcBeFb3Uq1qvWyRumYdk89Sro%3D</a>), 
  I would like to return to my main page.
  My problem is that this parameter is not zero, so I can not go back to the main page. My solution would be to use the fragments but I do not know how to do it. Could you help me.</p>
  
  <pre><code>protected void init(VaadinRequest vaadinRequest) {
      String retour=(String) vaadinRequest.getParameter("retour");
      if(retour!=null) {
          String mt=(String) vaadinRequest.getParameter("mt");
          String code=(String) vaadinRequest.getParameter("code");
          String key=(String) vaadinRequest.getParameter("key");
          traiteRetourPaiement(retour, mt, code, key);
      } else {
          String nomApp = getNomApp(vaadinRequest);
          setContent(new DynamicView(nomApp));
      }
  }
  </code></pre>