From 8891204b820afb962d75f21f515ebe92e05d6f0a Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Thu, 3 Nov 2016 20:28:12 -0400
Subject: [PATCH] Don't load Chunks from Hoppers and other things

Hoppers call this to I guess "get the primary side" of a double sided chest.

If the double sided chest crosses chunk lines, it causes the chunk to load.
This will end up causing sync chunk loads, which will unload with Chunk GC,
only to be reloaded again the next tick.

This of course is undesirable, so just return the loaded side as "primary"
and treat it as a single chest if the other sides are unloaded

diff --git a/src/main/java/net/minecraft/server/BlockChest.java b/src/main/java/net/minecraft/server/BlockChest.java
index 5fd6061f60..af18759ee4 100644
--- a/src/main/java/net/minecraft/server/BlockChest.java
+++ b/src/main/java/net/minecraft/server/BlockChest.java
@@ -227,7 +227,12 @@ public class BlockChest extends BlockTileEntity implements IBlockWaterlogged {
                 return blockchest_chestfinder.b(tileentitychest);
             } else {
                 BlockPosition blockposition1 = blockposition.shift(j(iblockdata));
-                IBlockData iblockdata1 = generatoraccess.getType(blockposition1);
+                // Paper start - don't load chunks if the other side of the chest is in unloaded chunk
+                IBlockData iblockdata1 = generatoraccess.getTypeIfLoaded(blockposition1);
+                if (iblockdata1 == null) {
+                    return null;
+                }
+                // Paper end
 
                 if (iblockdata1.getBlock() == iblockdata.getBlock()) {
                     BlockPropertyChestType blockpropertychesttype1 = (BlockPropertyChestType) iblockdata1.get(BlockChest.b);
-- 
2.21.0