Vaadin 10 Payment Request API demo problem

Hi,

I have checked out the Vaadin 10 Payment Request API demo from https://github.com/Wnt/PaymentRequestAddon , but unfortunately I have weird problem with running it in the browser. The browser just shows a blank window with unfinished loading indicator, while developer tools show that the page is loaded with some reasonable content.

I run the demo from Eclipse and access it at http://localhost:8080/ using Chrome and Edge with the same result. The only possibility for me to see the page content is to stop the server. Then the page is displayed with no CSS applied.

I have no errors in the startup log, just a single warning: “[qtp1745701482-17]
WARN com.vaadin.flow.server.DefaultDeploymentConfiguration -”.

What may be the problem? Any ideas and comments are most welcome…

Thanks in advance,
Sergey