[Gameplay] Graves E Not Reducing CD When Attacking Structures

I do not know if this is intended, but it is not included in the tooltip so I assume it isn't. When you use Graves' E (Quickdraw) and auto-attack a turret, inhibitor, or nexus, the cooldown does NOT reduce by 1 second per attack. After noticing this in a ranked game, I replicated this in a custom game, making sure to attack every single structure (all 11 towers, 3 inhibs, and nexus) on the map after using E and none of them reduced the cooldown of the spell. However, it appears to work normally against minions and champions.