So... I checked out the code (fortunately they use git)
and looking at pom.xml, the version history was like 2.1.11-SNAPSHOT --> 2.1.11 --> 2.1.12-SNAPSHOT --> 2.3.0-SNAPSHOT
It seems the last release was 2.1.11, and then they planned to do 2.1.12 but then move up to 2.3.0
Also the repo has branch jaxb-2_2_11-branch but no jaxb-2_2_12-branch
EDIT: I was referring to jaxb-ri repo, so maybe it's not what you're looking for. Sorry for the confusion.