From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 17 Oct 2018 19:17:27 -0400
Subject: [PATCH] MC-50319: Check other worlds for shooter of projectiles

Say a player shoots an arrow through a nether portal, the game
would lose the shooter for determining things such as Player Kills,
because the entity is in another world.

If the projectile fails to find the shooter in the current world, check
other worlds.

diff --git a/src/main/java/net/minecraft/world/entity/projectile/Projectile.java b/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
index cadcd3060e1c0e459ea064d2ac7a3ab5a4214d1d..80fdb953d7a49b05108672e18ea326182fa7cfd6 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
@@ -57,6 +57,18 @@ public abstract class Projectile extends Entity {
             return this.cachedOwner;
         } else if (this.ownerUUID != null && this.level instanceof ServerLevel) {
             this.cachedOwner = ((ServerLevel) this.level).getEntity(this.ownerUUID);
+            // Paper start - check all worlds
+            if (this.cachedOwner == null) {
+                for (final ServerLevel level : this.level.getServer().getAllLevels()) {
+                    if (level == this.level) continue;
+                    final Entity entity = level.getEntity(this.ownerUUID);
+                    if (entity != null) {
+                        this.cachedOwner = entity;
+                        break;
+                    }
+                }
+            }
+            // Paper end
             return this.cachedOwner;
         } else {
             return null;