Why my simple Spring Boot application fails to deploy on Heroku? [closed]

I’m just trying to deploy a very simple spring boot app in Heroku, but despite showing no errors in the deploy log, it doesn’t works.

When I open it in the browser at the deployed address, it shows this message:

**Whitelabel Error Page

*This application has no explicit mapping for /error, so you are seeing this as a fallback.

Mon Apr 05 08:47:38 UTC 2021
There was an unexpected error (type=Not Found, status=404).***

I am using Git Hub connect ad Heroku deployment method.
This is the code I deployed from my public repository:
https://github.com/Picpippo/hello-heroku789.git

There are no errors in heroku, on the contrary it shows me all green ticks.
So, what’s wrong with it?
Thanks

Answer

I think that there is nothing mapped on the root URL. However There is a controller listening on /hello path.
Try this URL: https://hello-heroku789.herokuapp.com/hello