Paper/patches/server/0331-Fix-items-vanishing-through-end-portal.patch

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 31c1e5c5e0ccd1c7bd65e5f52121f0af444f73fa..2c8e2ed7199c33f5c4fe25faa9f60fa74982de35 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -3410,6 +3410,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
             if (flag1) {
                 blockposition1 = ServerLevel.END_SPAWN_POINT;
             } else {
+                destination.getChunkAt(destination.getSharedSpawnPos()); // Paper - Ensure spawn chunk is always loaded before calculating Y coordinate
                 blockposition1 = destination.getHeightmapPos(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES, destination.getSharedSpawnPos());
             }
             // CraftBukkit start