Stephan Schroevers

Older versions [were](https://repo1.maven.org/maven2/com/ullink/slack/simpleslackapi/) pushed to Maven Central. This practice was abandoned?

> I haven't had time to investigate much yet. Same here; yesterday I tried to reproduce it using a tiny unit test, but that failed. Next up would be to...

I'm fine closing this PR as-is, though OTOH such a checker could save us quite some time when open-sourcing the code base. How was the current changeset generated, and could...

Yep, likely! Too bad it's [all `private`](https://github.com/google/error-prone/blob/9f8c332d9ea67dfd31d8a91a023392f61097ae8a/core/src/main/java/com/google/errorprone/bugpatterns/CanonicalDuration.java#L60), so that would entail some copying. Alternatively we could try to contribute improvements upstream, possibly by extracting shared logic to a separate class....

Updated the milestone. As discussed offline, we'll merge this PR once `error-prone-support` depends on a version of Error Prone (or our fork) that includes google/error-prone#2706.

Dropped this ticket from the upcoming milestone for now. Not because we don't want this change, but because we first need to formulate a solution to the "serialization compatibility question".

> Other option would be to create a check that detects we don't need the type arguments.... That sounds more complex, but on the plus side would enable also other...

Rebased and resolved conflicts.

The current state of the PR contains a Surefire upgrade, as it relied on functionality only available in a milestone release. This upgrade is now part of #532, to be...

I filed #603 for the Jabel build changes; once merged the scope of this PR will be reduced to just the `CompilationTestHelper`/`BugCheckerRefactoringTestHelper` text block formatting support.