@Override
        public boolean mayPickup(Player player) {
            // Dont allow pickup if this is the slot containing the selected backpack
            return getSlotIndex() != player.getInventory().selected;
        }
Slot for the actual player inventory. Disables picking up backpack from hotbar.
exploration/src/main/java/mrtjp/projectred/exploration/inventory/container/BackpackMenu.java