Paypal IPN Listener java example?

Question

Java

Hello, please tell me who did the PayPal integration in Java. And then for the second hour I can’t google anything sensible ...
You need to configure IPNListener.
I have a springboot application.
So far I found this, but it does not help me much.
https://github.com/paypal/sdk-core-java/blob/maste...
So what questions do I have.
Is there a class somewhere with all the different fields that PayPal will send me? Or it is necessary to get everything handles from request?
How to test IPNListener? In the test account settings, you can enter the url, but I doubt that I will enter localhost there and it will work ...
Well, or a link to some resource with a java (spring) example.
Thank you!