Hey,
i've run SonarQube on the Spring Boot codebase and started to add some Assert.notNull calls where we use references which can be null and the static analysis checker complained. These were often cases where we call a @Nullable annotated method and then call methods on the returned reference without checking for null.
Besides that the static analysis found other things, which i fixed.
We have to decide if we want those Asserts in our codebase. Could help if we decide into things like ErrorProne or NullAway or use @Nullable ourselves.
The PR is quite a hodgepodge of different changes, if there's a chance to merge it into the codebase, I can clean it up and separate the changes more.
Comment From: mhalbritter
I ported all important and not null related changes to main. We can close this now.