Prefer constructor injection

[juherr]

First baby step for #1202

[juherr]

Ping @goekay

[juherr]

Ping @goekay

[juherr]

Ping @goekay Should I close or update this PR?

[juherr]

The Spring team generally advocates constructor injection, as it lets you implement application components as immutable objects and ensures that required dependencies are not null. Furthermore, constructor-injected components are always returned to the client (calling) code in a fully initialized state. As a side note, a large number of constructor arguments is a bad code smell, implying that the class likely has too many responsibilities and should be refactored to better address proper separation of concerns.

(https://docs.spring.io/spring-framework/reference/core/beans/dependencies/factory-collaborators.html)