Additional comments inline:

If there were a general test, I imagine one could test the DataStore interface rather than that ContentDataStore interface/abstract implementation.  (For GeoMesa, we ended up going with the Abstract** implementations since some class element had too restrictive of permissions at one point.)

Darn, I am trying to kill AbstractDataStore classes. Would of loved to know what permissions were getting in your way. The geotools-devel list here is for exactly these kind of questions.  

Anyhow, is a back-port to the 11.x series possible?  In reality, that likely only matters if the 11.3 release will come before the 12.0 release...

The release schedule is available: https://github.com/geoserver/geoserver/wiki/Release-Schedule

Jody