Closely relates to MC-125351 (not a duplicate as the spawner isn't a partial block). As that ticket wasn't resolved as a feature request, I don't think this one would qualify as a feature request either.

The bug

In 22w12a, the ability to waterlog leaves, a presumably hollow cube, was added, similarly to how roots, another hollow cube, were able to in the previous snapshot. However, spawners, which are also presumably yet another hollow cube, cannot be waterlogged.

How to reproduce

1. Use a water bucket on leaves
2. Use a water bucket on a spawner

Expected results

Water would be placed inside of the leaves and inside of the spawner.

Actual results

Water is placed inside of the leaves, but only to the side of the spawner.