Getting placed item in InventoryClickEvent

Hey. I am trying to make a plugin where players can deposit one item into an inventory, and then the item is saved to the config file. I've made a nine slot inventory and filled up all except one slot. Now, here's my code for my InventoryClickEvent listener

Code:

    @EventHandler
    public void invClick(InventoryClickEvent e) {
        if (e.getClickedInventory().equals(Create.menu)) {
            if (e.getAction().equals(InventoryAction.PLACE_ALL)) {
                e.getWhoClicked().getInventory().addItem(e.getCurrentItem()); //for debugging
            } else {
                e.setCancelled(true);
            }
        }
    }

What I'm having trouble with is getting the item. If I do

Code:

 e.getInventory().getItem(e.getSlot());

it returns null, and the first code just returns Material.AIR

How can I get the item that they placed in the inventory?

 

@TheMinecraftKnight So you know what is the slot ?
Listen on inventoryClose then get the item at the slot, check if it's not null and save to the config

 

@Caderape2 Yeah, I know the slot. They can only deposit the item in one slot, so yeah I do. That should work.