Spigot 1.13 checks if any field (which are manually copied from the ItemStack's "tag" NBT tag) on the ItemMeta class of an ItemStack is set.
We could just check if the "tag" NBT tag is empty, albeit that would break some plugins. The only general tag added on 1.13 is "Damage", and we can just check if the "tag" NBT tag contains any other tag that's not "Damage" (https://minecraft.gamepedia.com/Player.dat_format#Item_structure) making the `hasItemStack` method behave as before.
Check the `ItemMetaTest#testTaggedButNotMeta` method to see how this method behaves. (I also added some extra tests).
`hasItemMeta()` will return true if `ItemStack.getDamage() != 0` or it has the `Damage` tag or any other tag is set.
Closes#1222
Aikar
Hugo Manrique