Minecart with Monster Spawner

Minecarts with spawners are a combination of both minecarts and spawners.

Obtaining
Minecarts with spawners cannot be obtained as an item in the inventory, and can only be produced using the command.

Usage
The spawner within behaves the same way as normal spawners; but the entity to be spawned cannot be set via using Spawn Eggs; the spawner's data can only be modified using commands or NBT edits. It has the same associated NBT tags as a normal spawner.

More preicsely, a spawner minecart acts as a spawner block at the minecart's position. In other words, if the spawner minecart moved within a block position, the range of spawn would not change, but if it moved 5 blocks east, the range of spawn would now be centered at the spawner minecart's new position.

Drops
When they are broken, spawner minecarts drop 1. The spawner will not drop.

Entity data
Minecarts with spawners have entity data associated with them that contain various properties of the entity.