Hi,
I noticed a comment by Kurt Schwer in the discussion of this Proj pull request
DRAFT: Yet another MEGA (Make ETRS89 Great Again) fix! by rouault · Pull Request #4736 · OSGeo/PROJ
I hope the GeoTools folks are following along so they can step over the troubles when the day comes that they update their EPSG db.
-Jukka Rahkonen-