Various "buckets" (bucketlib buckets, Mekanism fluid tank in bucket mode, and in the near future teapots from SimplyTea, etc) are not able to use the milk jars.

The main problem is that MilkJarBlock::useItemOn() specifically checks for and returns Items.BUCKET and Items.MILK_BUCKET, and any other bucket-like items will be ignored.

I tried to use Balm's useFluidTank method instead of the bucket pickup/place logic in MilkJarBlock::useItemOn(), and it seemed to work fine for filling any fluid handling items (including vanilla buckets) in Forge 1.20 but is not working in Forge/Neoforge 1.21 for some reason.

Is this still an issue in v21.1.3? Milk and Cow jars weren't registered as fluid handlers for NeoForge before which probably played a role.