My experience is that the regular drinks package, which a majority of folks in the haven have, only cover drinks up to $15 and soda from the gun.
If you have the premium plus drinks package they will give you the cans and bottled water.
Last cruise, my butler also told me right away he couldn't bring cans of coke to my room to stock the fridge, but when I suggested I would just bring them from the haven bar he kept them stocked the whole time. I think its for sure hit or miss, but the plus package is what enables cans - and it's an upcharge.