Create EntityItem

I’m having problems creating new EntityItems. I’ve tried using the following code (where player is the player)

Item item = (Item) player.getWorld().createEntity(EntityTypes.DROPPED_ITEM, player.getLocation().getPosition()).get();
item.offer(item.getItemData().item().set(itemStack));

item.getItemData just calls get on an absent Optional
How do I fix this?

The RepresentedItemData is not yet implemented, see

Oh, thank you, I thought the Data API was fully implemented.