EntityKnockbackByEntityEvent called with wrong entities

Expected behavior

The EntityKnockbackByEntityEvent#hitBy() entity should be called with the entity that did the knockback

Observed/Actual behavior

Instead, if the entity that did the knockback is a projectile or a TNT, the #hitBy entity is a player (shooter of the projectile or the one that lit the TNT) instead of the entity that actually did the knockback

Steps/models to reproduce

Example 1:

1. Throw a snowball
2. EntityKnockbackByEntityEvent will be called with #hitBy set to the shooter of the snowball instead of the actual snowball entity

Example 2:

1. Get a TNT and flint and steel
2. Prime the TNT
3. EntityKnockbackByEntityEvent will be called with #hitBy set to the player that primed the TNT instead of the TNT entity

Example 3:

1. /summon tnt
2. EntityKnockbackByEntityEvent will not be called because there was no entity that primed the TNT

Plugin and Datapack List

Only a plugin that was printing the #hitBy entity into the console. No datapacks.

Paper version

This server is running Paper version git-Paper-85 (MC: 1.18.1) (Implementing API version 1.18.1-R0.1-SNAPSHOT) (Git: df8d28a)
You are running the latest version

Other

No response

Start by tracing where EntityKnockbackByEntityEvent is created and where hitBy() is assigned for projectile and TNT knockback. Reproduce the snowball and primed-TNT cases, including summoned TNT, then verify that hitBy() is the projectile or TNT entity and that the event is emitted consistently.