Well whether the names are correct or not, there's not something called getProperty, so it wont work either way, that's way I asked if you were sure you could do getProperty. I have the correct names, so that's not really an issue. Just the method that doesn't makes sense, I have tried being a little creative and do .getProperties().equals(BlockSlab.TYPE) == SlabType.BOTTOM, that just gives an incompatible error.
EDIT: I'm an idiot sorry, .getProperty is just .get in 1.13.2, and it works fine