From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: chickeneer <emcchickeneer@gmail.com>
Date: Mon, 6 Sep 2021 02:05:16 -0500
Subject: [PATCH] Mitigate ConcurrentModificationException by copying
 entitySection access

Original code by Starlis, licensed under GNU General Public License v3.0
You can find the original code on https://github.com/starlis/empirecraft

diff --git a/src/main/java/net/minecraft/world/level/entity/PersistentEntitySectionManager.java b/src/main/java/net/minecraft/world/level/entity/PersistentEntitySectionManager.java
index bd7967680d7a75caff98a827895c795f2d101f99..a3acd40f24aae3c9809b76ce6f3e1b2d20acc5b1 100644
--- a/src/main/java/net/minecraft/world/level/entity/PersistentEntitySectionManager.java
+++ b/src/main/java/net/minecraft/world/level/entity/PersistentEntitySectionManager.java
@@ -264,23 +264,23 @@ public class PersistentEntitySectionManager<T extends EntityAccess> implements A
             if (flag2 && !flag3) {
                 entitysection.getEntities().filter((entityaccess) -> {
                     return !entityaccess.isAlwaysTicking();
-                }).forEach(this::stopTicking);
+                }).collect(Collectors.toList()).forEach(this::stopTicking); // EMC
             }
 
             if (flag && !flag1) {
                 entitysection.getEntities().filter((entityaccess) -> {
                     return !entityaccess.isAlwaysTicking();
-                }).forEach(this::stopTracking);
+                }).collect(Collectors.toList()).forEach(this::stopTracking); // EMC
             } else if (!flag && flag1) {
                 entitysection.getEntities().filter((entityaccess) -> {
                     return !entityaccess.isAlwaysTicking();
-                }).forEach(this::startTracking);
+                }).collect(Collectors.toList()).forEach(this::startTracking); // EMC
             }
 
             if (!flag2 && flag3) {
                 entitysection.getEntities().filter((entityaccess) -> {
                     return !entityaccess.isAlwaysTicking();
-                }).forEach(this::startTicking);
+                }).collect(Collectors.toList()).forEach(this::startTicking); // EMC
             }
 
         });