As it says in the title, isCooldown doesn't convey what the method does very well (it returns true if the stack has an active cooldown). hasCooldown or similar would be more appropriate and improve readability.
Why not ItemCooldownManager#isActive()?
Why not ItemCooldownManager#isActive()?
To me that would mean that the item isn't cooling down.
Why not just isCoolingDown?
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To me that would mean that the item isn't cooling down.
Why not just
isCoolingDown?