From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: AJMFactsheets <AJMFactsheets@gmail.com>
Date: Wed, 22 Jan 2020 19:52:28 -0600
Subject: [PATCH] Fix items vanishing through end portal

If the Paper configuration option "keep-spawn-loaded" is set to false,
items entering the overworld from the end will spawn at Y = 0.

This is due to logic in the getHighestBlockYAt method in World.java
only searching the heightmap if the chunk is loaded.

Quickly loading the exact world spawn chunk before searching the
heightmap resolves the issue without having to load all spawn chunks.

diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index c453a7df75d4486bf0123bc4932c441a707998b0..e707f3afe4cded677ab8d712e38063de2b5be90d 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -3175,6 +3175,9 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
             if (flag1) {
                 blockposition1 = ServerLevel.END_SPAWN_POINT;
             } else {
+                // Paper start - Ensure spawn chunk is always loaded before calculating Y coordinate
+                destination.getChunkAt(destination.getSharedSpawnPos());
+                // Paper end
                 blockposition1 = destination.getHeightmapPos(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES, destination.getSharedSpawnPos());
             }
             // CraftBukkit start