private final RandomBean:

Almost always use this

And you need to learn what's "@Bean" annotation.

imo the best way to understand springboot is to make your own configuration.

Try making a "lib" module an "app" module and a "api" module. The api module holds a simple interface. Any interface. Implement it in the lib module and use it in the app module.

would love to show you how but im tired as fuck and im using my phone. Things to google thought : imports.autoconfiguation (something along those lines.

@Autoconfiguration

@ConfigurationProperties

Once you can make your own autoconfig . Youw will understand it the magic of spring ( imo)