The Bug
The monster spawners, as it called now, still drops XP, when it has no mobs contains it (i.e. empty)

How to Reproduce
1. Get an empty monster spawner from the creative menu.
2. Place an empty monster spawner.
3. Switch to survival mode.
4. Mine it.

Observed Result
The empty spawner drops XP, even though there is no mobs inside of the cage.

Expected Result
The empty spawner should not drop XP, because there is nothing inside the cage.