I would like to be able to open the inventory of a donkey with a chest by code

Currently I get the error: Unsupported custom inventory size 17
Used code:
Player player = event.getPlayer();

Donkey donkey = (Donkey) Objects.requireNonNull(player.getWorld()).spawnEntity(new Location(player.getWorld(), 0,62,0), EntityType.DONKEY);
donkey.setCarryingChest(true);
player.openInventory(donkey.getInventory());