From 8b7b6d6567969fde109ee4cc9ff7f4cd95823fa3 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 ee9d91a8c..e71178ac1 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