From c2ab89098d7c955345d923a6e50b9b476986ec08 Mon Sep 17 00:00:00 2001
From: CraftBukkit/Spigot <noreply+git-craftbukkit@papermc.io>
Date: Mon, 26 Aug 2019 19:24:09 +1000
Subject: [PATCH] SPIGOT-5287: Fix rare CME generating new chunks

By: md_5 <git@md-5.net>
---
 .../nms-patches/DefinedStructureManager.patch         | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 paper-server/nms-patches/DefinedStructureManager.patch

diff --git a/paper-server/nms-patches/DefinedStructureManager.patch b/paper-server/nms-patches/DefinedStructureManager.patch
new file mode 100644
index 0000000000..d1bdcca564
--- /dev/null
+++ b/paper-server/nms-patches/DefinedStructureManager.patch
@@ -0,0 +1,11 @@
+--- a/net/minecraft/server/DefinedStructureManager.java
++++ b/net/minecraft/server/DefinedStructureManager.java
+@@ -20,7 +20,7 @@
+ public class DefinedStructureManager implements IResourcePackListener {
+ 
+     private static final Logger LOGGER = LogManager.getLogger();
+-    private final Map<MinecraftKey, DefinedStructure> b = Maps.newHashMap();
++    private final Map<MinecraftKey, DefinedStructure> b = Maps.newConcurrentMap(); // SPIGOT-5287
+     private final DataFixer c;
+     private final MinecraftServer d;
+     private final java.nio.file.Path e;