Potions no longer use durability/data values to identify themselves as a certain type. This means any plugin that uses durabilities to give potions no longer work, and to give a potion we must use NBT tags. However, many people don't know how to use NBT tags and it's also a bit complicated. It'd be a lot easier if Spigot could implement some support of NBT tags and getting the potion type from an item, and potentially fix their Potion class.

This may be a 'duplicate', but I'd like to put this on Major priority as I know that many plugins are awaiting some kind of potion update and there is no 'easy' workaround.
Personally, I cannot update KingKits to 1.9 as the kit deserialization for potions is broken now.