EntitySpawnEvent with optional source ItemStack

[Prof-Bloodstone]

Is your feature request related to a problem? Please describe.
I'd love to be able to modify the entity when it gets spawned from some ItemStack (spawn egg, boat, item frame, ...) and act on that.

Describe the solution you'd like
Ability to retrieve to retrieve source ItemStack which caused the Entity to spawn.
I think it'd make most sense to add it as nulllable value to existing EntitySpawnEvent, since other events like CreatureSpawnEvent and ProjectileLaunchEvent might potentially also use this.

Describe alternatives you've considered
Patching the server source code directly :/

[Proximyst]

I've looked into this before, and it's a tedious process to say the least. PRs welcome, but not a beginner issue :p

[Machine-Maker]

There's no overriden method for example to create an entity from an item, so this would probably have to be done for each item that does this which requires a list of items that do it

• Spawn Eggs
• Boats
• Item Frame (HangingPlaceEvent)
• Painting (HangingPlaceEvent)
• Leash (HangingPlaceEvent)
• Armor Stand
• End Crystals
• Fish Buckets
• Fireworks

and what am I missing?