Using IFrame component (vaadin 14)

Hi all,
I’m new to Vaadin, and I’m trying to use, modifiy and combine some examples.
I executed the vaadin tutorial (Building Modern Web Apps with Spring Boot and Vaadin.pdf) and I’m now trying to replace the content with an Iframe, in which I’ll load another application/url. I can load external url (http://www…) and navigate the loading vaadin application without problem.
When the url is another local vaadin application, the application loads fine in the iframe, but if i navigate the loading app, the whole page reloads, and I’m redirected to the login screen of the loading app.
Would anyone have any suggestions to what the problem might be?

I probably found the problem: a coockie issue: every vaadin application uses a cockie, and if you use multiple vaadin application in the same page, the cookie will be overwritten.
I solved adding property in file.