From b088e781bdb0c1f995db5e4865791f7aeb6c401e Mon Sep 17 00:00:00 2001
From: Brokkonaut <hannos17@gmx.de>
Date: Fri, 20 Oct 2017 04:33:45 +0200
Subject: [PATCH] Replace HashSet with fastutil's ObjectOpenHashSet in
 HashTreeSet

HashSet sometimes uses compareTo() instead of equals() and this breaks the comparison of net.minecraft.server.NextTickListEntry (the only place where HashTreeSet is used).

In this cases duplicate entries could be added to the HashSet of HashTreeSet, because NextTickListEntry.compareTo() does not return 0, even if NextTickListEntry.equals() returns true.

ObjectOpenHashSet never uses compareTo(), so the inconsistencies of NextTickListEntry cause no problems.

Fixes https://github.com/PaperMC/Paper/issues/588

diff --git a/src/main/java/org/bukkit/craftbukkit/util/HashTreeSet.java b/src/main/java/org/bukkit/craftbukkit/util/HashTreeSet.java
index 80a5c29f3b..cd864c4047 100644
--- a/src/main/java/org/bukkit/craftbukkit/util/HashTreeSet.java
+++ b/src/main/java/org/bukkit/craftbukkit/util/HashTreeSet.java
@@ -8,7 +8,7 @@ import java.util.TreeSet;
 
 public class HashTreeSet<V> implements Set<V> {
 
-    private HashSet<V> hash = new HashSet<V>();
+    private Set<V> hash = new it.unimi.dsi.fastutil.objects.ObjectOpenHashSet<V>(); //Paper - Replace java.util.HashSet with ObjectOpenHashSet
     private TreeSet<V> tree = new TreeSet<V>();
 
     public HashTreeSet() {
-- 
2.18.0