There are multiple classes are implementing interfaces, and then in a third class where we have autowired list, now I have made another class and extend it from the interface but its beans don't get registered
That's not how the Spring autowiring mechanism works. You marked a field that is of type List<A> to be autowired. I doubt that's even possible because of generics type erasure. Search for more info about how autowiring in Spring works. This article looks ok: https://howtodoinjava.com/spring/spring-core/spring-beans-autowiring-concepts/