Spring @Lookup annotation tutorial.

This is a quick proof of concept of Spring's method-level dependency injection support via the @Lookup annotation. It is based on Baeldung's tutorial "@Lookup annotation in Spring".

Limitations:

- @Lookup-annotated methods, like getNotification, must be concrete when the surrounding class, like Student,
is component-scanned. *This is because component scanning skips abstract beans.*
- @Lookup-annotated methods won’t work at all when the surrounding class is @Bean-managed.