[KamBha]

I find this argument a little odd:-

"Frameworks do not keep retro-compatibility"

I would argue that is a good thing and in the case of Spring, doesn't feel true. In part, Spring is so hard to learn because it has too much support for legacy stuff (though this may have changed in the last few years).

The only issue with not supporting retro-compatibility is because the JVM doesn't support retro compatibility. I recently tried to upgrade an application to the latest version of Java (I think it was Java 12) and found that date formaters were completely changed to match an ISO standard which broke a lot of code. We also found a similar problem with the Java 8 transition as well forcing a huge upgrades to our libraries.

I am of the view that libraries and frameworks should support not support retro compatibility but the language should. This way, if you don't want to upgrade your library then you don't have to.

Using the web as an example, old Angular JS applications still work today as they did back when they were first written. I doubt applications written in the first version of Spring will work with the latest version of the JVM.