InventoryMoveItemEvent is fired when minecart-hoppers are under chests even though the minecart inventory is full (when items cannot be transferred).

Additionally, under those circumstances it also seems to fire about once per tick per itemstack in the upper inventory. A single full minecart-hopper under a full doublechest will trigger ~54 events each tick (~1080 per second). You can easily test this with a timings report and a plugin that listens to the event.

To reproduce:

1. Place a rail
2. Place a double chest on top of the rail
3. Place a minecart hopper on the rail
4. Fill the minecart hopper completely
5. Place at least 1 item in each slot of the double chest

Here's a sample timings report with a plugin that listens to these events but does nothing. 

@EventHandler(ignoreCancelled = true, priority = EventPriority.NORMAL)
public void onInventoryMove(InventoryMoveItemEvent event){
  //nothing
}