Problem with BlockDispenseEvent

My code:

Code:

@org.bukkit.event.EventHandler(priority=EventPriority.HIGHEST)
public void BlockDispense(BlockDispenseEvent e){
    System.out.println("DISPENSED");
    Block block = e.getBlock();
    final Dispenser dispenser = (Dispenser)block.getState();

    e.setItem(new ItemStack(Material.BARRIER));
    ItemStack itm = dispenser.getInventory().getItem(4);
    System.out.println(itm);
}

I set it to dispense barriers to not touch any of the items inside. So I can activate the dispenser as many times as I want and the contents won't change. Good. That's what I want. Now I need to read the dispenser's contents so I can modify it. But there is a problem...

When I put 13 crafting tables in the middle the console says,
[22:31:07 INFO]: DISPENSED
[22:31:07 INFO]: ItemStack{WORKBENCH x 12}

No matter how many times I activate the dispenser it says there are 12 even though I looked back and there were still 13.

And when I put one in it says,
[22:32:29 INFO]: DISPENSED
[22:32:29 INFO]: null

How am I supposed to change the contents properly if I can't read what's inside?

 

Have you tried looping trough the contents of the dispenser and printing them out?

 

Yes.

Show Spoiler Hide Spoiler

[17:43:03 INFO]: SEARCHED SLOT0
[17:43:03 INFO]: null
[17:43:03 INFO]: SEARCHED SLOT1
[17:43:03 INFO]: null
[17:43:03 INFO]: SEARCHED SLOT2
[17:43:03 INFO]: null
[17:43:03 INFO]: SEARCHED SLOT3
[17:43:03 INFO]: null
[17:43:03 INFO]: SEARCHED SLOT4
[17:43:03 INFO]: ItemStack{WORKBENCH x 12}
[17:43:03 INFO]: SEARCHED SLOT5
[17:43:03 INFO]: null
[17:43:03 INFO]: SEARCHED SLOT6
[17:43:03 INFO]: null
[17:43:03 INFO]: SEARCHED SLOT7
[17:43:03 INFO]: null
[17:43:03 INFO]: SEARCHED SLOT8
[17:43:03 INFO]: null

Ok I'll try that.
EDIT: Same thing,
[17:18:13 INFO]: WORKBENCH 12

 

I'm guessing that the BlockDispenseEvent removes the item before canceling, and adds it back after.