Some time ago the project maven-jaxb2-plugin was orphaned because Alexey Valikov sadly passed away. Thankfully, Rick O'Sullivan stepped into the breach a short time later and did a great job with hisrc-basicjaxb & Co. and continued the whole thing in a magnificent way.
I have some outdated code in front of me right now and need to change the namespace from javax to jakarta. Rather by chance I noticed that Laurent Schoelens and Matt Pavlovich have taken over the original repository maven-jaxb2-plugin and are also working very diligently on the continuation of the original project meanwhile under jaxb-tools. Furthermore, there is Philip Helger who is developing another fork under the original name maven-jaxb2-plugin.
I just wanted to check whether everyone involved knows about each other. I think it is simply a waste of resources for the few willing and capable developers to do the same work twice and three times without any real added value. In my opinion, it would make much more sense to join forces and either reduce the effort of the individual participants and/or be able to develop additional features. If any of the people involved reads this, I would be interested to know whether there are or could be efforts to continue the work together in the future.
As discussed on github issue you created, our goal with Matt was (and still is) to maintain the original repository (in fact repositories since we did merge the related jaxb-tools into maven-jaxb2-plugin one, renamed jaxb-tools), which both projects you mention are forked from.
We're not closed to any PR from anyone. It'd be easier to maintain only one repo, and since now we have active dev here, maybe it'd be a good start, but I don't want to force anyone to choose one repository or another : everyone's work is valuable and what phax and patrodyne did helped people when Alexey passed away (sadly).
EDIT 2024
Philip's repository phax/maven-jaxb2-plugin is now archived and pointing to highsource/jaxb-tools.
I've added corresponding section in migration guide.