I've been working as first a Python and then a Java dev for the last 15 years and I can count the amount of times when I've seen actual OOP on one hand.

I mean, we write "class" at the beginning of our modules and at the beginning of our structs, and we write "interface" at the beginning of our header files, but none of that is actually OOP.

If you use Spring Boot, you are essentially doing C (not even C++) in Java.

You have data-only classes without methods (at best there's a conversion method or something shallow like that) that work identical to C structs. You have service interfaces, which serve the same purpose as C header files. And then you have data-less collections of functions (service/controller classes), which work like .c files.

Nowhere in this whole process are you actually using OOP techniques.