Add support for Spring Boot 3

[wormangel]

What's changed

• Make library compatible with Spring Boot 3
  • Fix autoconfiguration (META-INF path changed)
  • Replace javax.* imports with corresponding jakarta.* ones
  • Rename module: nakadi-producer-starter-spring-boot-2-test -> nakadi-producer-starter-spring-boot-3-test
  • Replace a few other imports with their new updated locations
• Change deprecated Docker images
• Bump Java version to 21 LTS
• Remove org.postgresql as it's already covered in other dependency
• Bump several dependencies' versions
• Update README with new instructions regarding version of the library vs. version of Spring Boot
• Add Github CI Action to trigger a Maven build
• Bump library version to 30.0.0-SNAPSHOT

Notes

• Thanks to @Hassan for the initial work in [DO NOT MERGE] WIP: Migrating into Spring Boot 3 #189
• Thanks to @roskenet for highlighting the needed autoconfiguration changes in Migration to SpringBoot 3.x #186

[wormangel]

@ePaul I wanted to trigger a build with a GH action but I guess the PR needs to be merged first for the .github/workflows/ci.yml to have effect (or some other action is needed from the owner of the repo?)

[ePaul]

So there is no way of having a version of the library which works with both Spring boot 2 and 3?

[wormangel]

Not in my understanding - the 'small' changes in Spring Boot 3 (namely the Jakarta EE 10 + Flyway 9 adoption, and the lack of support for the old way of specifying autoconfiguration) are incompatible between the two versions.

[ePaul]

@ePaul I wanted to trigger a build with a GH action but I guess the PR needs to be merged first for the .github/workflows/ci.yml to have effect (or some other action is needed from the owner of the repo?)

Hmm, not sure. I don't see any button like "run checks". Maybe you can submit the changes to set up a CI separately?
(Though we'll likely soon move this repository to our internal Github, and then we can just use CDP.)

[wormangel]

@ePaul I wanted to trigger a build with a GH action but I guess the PR needs to be merged first for the .github/workflows/ci.yml to have effect (or some other action is needed from the owner of the repo?)

Hmm, not sure. I don't see any button like "run checks". Maybe you can submit the changes to set up a CI separately? (Though we'll likely soon move this repository to our internal Github, and then we can just use CDP.)

In that case I might just wait for that then (also volunteer to help with the move) - otherwise the PR now would have to initially run a build with JDK 11, that would cause a merge conflict here, etc.. too much hassle.

[ePaul]

I just was looking at this again, and noticed that this test isn't actually executed when building the project (e.g. with mvnw clean install).

I was just going to complain, but then I also ran the build in master, and found that the test isn't run spring-boot 2 either :-/

I don't remember anymore whether we intentionally disabled this to get the build running faster ... but in effect I can't get it to run now. Any ideas?

[wormangel]

I didn't try to fix this myself (could try later if needed) but it smells to me like mixup between JUnit 4 and 5 (and/or JUnit 4 vs. recent Spring Boot issues) - I faced similar things in the past and it was related to that (the fix was to move everything to JUnit 5 instead of having this versions spaghetti (e.g. get rid of @RunWith(SpringRunner) in favor of only @SpringBootTest, etc)