Use constructor binding for Spring Bean dependencies instead of field injection

[aegan123]

The recommended way of injecting Spring Bean dependencies is to use constructor binding instead of field injection with @Autowired annotation.

With Lombok annotations constructors can be automatically generated so handling it this way is easy.

SonarQube explains it as:
"Dependency injection frameworks such as Spring, Quarkus, and others support dependency injection by using annotations such as @Inject and @Autowired. These annotations can be used to inject beans via constructor, setter, and field injection.
Generally speaking, field injection is discouraged. It allows the creation of objects in an invalid state and makes testing more difficult. The dependencies are not explicit when instantiating a class that uses field injection.
In addition, field injection is not compatible with final fields. Keeping dependencies immutable where possible makes the code easier to understand, easing development and maintenance.
Finally, because values are injected into fields after the object has been constructed, they cannot be used to initialize other non-injected fields inline."

[Nonononoki]

I'm fairly certain sonarqube also flags methods with more than 7 parameters, which is conveniently hidden using lombok. In cases like EventListenerConfig and AdminService, I'd like to have Lombok's Builder instead of RequiredArgsConstructor so the code remains readable.

[aegan123]

I'm fairly certain sonarqube also flags methods with more than 7 parameters,

It typically does. Since EventListenerConfig and AdminService are Spring Beans you won't see that happen with Lombok's generated methods. For non Spring Beans classes builders are very nice (use them myself as well) but you don't manually manage Spring Beans or instantiate them (outside (unit) tests at least) so the amount of parameters becomes irrelevant (though generally speaking less is better) thus builders aren't usable with Spring Bean classes. You can use @Builder if you like for nicer usage in tests. When you also have @Value fields in your bean classes it becomes a bit messier since you can't use @AllArgsConstructor and have to use @NonNull on injectable Spring Bean fields.