Show async behavior with CompletableFuture in examples/documentation

[manuel-mauky]

We should provide an example of how to use CompletableFuture to implement async behavior.

[gtnarg]

If you are able to add an unpolished example here (prior to closing this issue) it would be appreciated as I have a need for this :)

[manuel-mauky]

Hi,
I've added a small app with a backend service that simulates delays and sometimes "connection error".
In the frontend I've used CompletableFuture to handle async usage of the backend service and error handling.

Take a look at the example and tell me what you think.

[gtnarg]

This is great - thank you very much for the quick response!

I will review and let you know if I have any questions or feedback.