Paper/Spigot-Server-Patches/0712-fix-PlayerItemHeldEvent-firing-twice.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: chickeneer <emcchickeneer@gmail.com>
Date: Thu, 22 Apr 2021 19:02:07 -0700
Subject: [PATCH] fix PlayerItemHeldEvent firing twice


diff --git a/src/main/java/net/minecraft/network/protocol/game/PacketPlayInHeldItemSlot.java b/src/main/java/net/minecraft/network/protocol/game/PacketPlayInHeldItemSlot.java
index d68f3e6b35f0af846c8a66710c5752508c095179..0e8ee44d0104ca7c666f57bdb54e0957935d5b34 100644
--- a/src/main/java/net/minecraft/network/protocol/game/PacketPlayInHeldItemSlot.java
+++ b/src/main/java/net/minecraft/network/protocol/game/PacketPlayInHeldItemSlot.java
@@ -24,6 +24,7 @@ public class PacketPlayInHeldItemSlot implements Packet<PacketListenerPlayIn> {
         packetlistenerplayin.a(this);
     }
 
+    public int getItemInHandIndex() { return b(); } // Paper - OBFHELPER
     public int b() {
         return this.itemInHandIndex;
     }
diff --git a/src/main/java/net/minecraft/server/network/PlayerConnection.java b/src/main/java/net/minecraft/server/network/PlayerConnection.java
index 6ad075907d56a8f41ca3a7b82ff90a6d3ad9f1d4..b543776da3b799643893984a8c6f29477ed78d4a 100644
--- a/src/main/java/net/minecraft/server/network/PlayerConnection.java
+++ b/src/main/java/net/minecraft/server/network/PlayerConnection.java
@@ -1903,6 +1903,7 @@ public class PlayerConnection implements PacketListenerPlayIn {
         PlayerConnectionUtils.ensureMainThread(packetplayinhelditemslot, this, this.player.getWorldServer());
         if (this.player.isFrozen()) return; // CraftBukkit
         if (packetplayinhelditemslot.b() >= 0 && packetplayinhelditemslot.b() < PlayerInventory.getHotbarSize()) {
+            if (packetplayinhelditemslot.getItemInHandIndex() == this.player.inventory.itemInHandIndex) { return; } // Paper - don't fire itemheldevent when there wasn't a slot change
             PlayerItemHeldEvent event = new PlayerItemHeldEvent(this.getPlayer(), this.player.inventory.itemInHandIndex, packetplayinhelditemslot.b());
             this.server.getPluginManager().callEvent(event);
             if (event.isCancelled()) {