Learning spring core by experimentation
- https://www.youtube.com/watch?v=If1Lw4pLLEo&t=3384s
- https://www.baeldung.com/constructor-injection-in-spring
- https://stackoverflow.com/questions/11903053/difference-between-component-and-configuration-in-spring-3
- https://stackoverflow.com/questions/4203302/how-to-inject-a-value-to-bean-constructor-using-annotations
- https://stackoverflow.com/questions/2902335/instantiating-multiple-beans-of-the-same-class-with-spring-annotations
- https://stackoverflow.com/questions/4447877/how-does-spring-autowire-by-name-when-more-than-one-matching-bean-is-found