Paper/patches/server/0551-Fix-PlayerBucketEmptyEvent-result-itemstack.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Thu, 20 May 2021 22:16:37 -0700
Subject: [PATCH] Fix PlayerBucketEmptyEvent result itemstack

Fixes SPIGOT-2560: https://hub.spigotmc.org/jira/projects/SPIGOT/issues/SPIGOT-2560

diff --git a/src/main/java/net/minecraft/world/item/BucketItem.java b/src/main/java/net/minecraft/world/item/BucketItem.java
index 7617b6a0ad44e8b135d071836dc30df5ad062c42..6caed156ed0cfe0017d578f58cb963ee68272d78 100644
--- a/src/main/java/net/minecraft/world/item/BucketItem.java
+++ b/src/main/java/net/minecraft/world/item/BucketItem.java
@@ -40,6 +40,8 @@ import org.bukkit.event.player.PlayerBucketFillEvent;
 
 public class BucketItem extends Item implements DispensibleContainerItem {
 
+    private static @Nullable ItemStack itemLeftInHandAfterPlayerBucketEmptyEvent = null; // Paper - Fix PlayerBucketEmptyEvent result itemstack
+
     public final Fluid content;
 
     public BucketItem(Fluid fluid, Item.Properties settings) {
@@ -125,6 +127,13 @@ public class BucketItem extends Item implements DispensibleContainerItem {
     }
 
     public static ItemStack getEmptySuccessItem(ItemStack stack, Player player) {
+        // Paper start - Fix PlayerBucketEmptyEvent result itemstack
+        if (itemLeftInHandAfterPlayerBucketEmptyEvent != null) {
+            ItemStack itemInHand = itemLeftInHandAfterPlayerBucketEmptyEvent;
+            itemLeftInHandAfterPlayerBucketEmptyEvent = null;
+            return itemInHand;
+        }
+        // Paper end - Fix PlayerBucketEmptyEvent result itemstack
         return !player.hasInfiniteMaterials() ? new ItemStack(Items.BUCKET) : stack;
     }
 
@@ -182,6 +191,7 @@ public class BucketItem extends Item implements DispensibleContainerItem {
                     ((ServerPlayer) entityhuman).getBukkitEntity().updateInventory(); // SPIGOT-4541
                     return false;
                 }
+                itemLeftInHandAfterPlayerBucketEmptyEvent = event.getItemStack() != null ? event.getItemStack().equals(CraftItemStack.asNewCraftStack(net.minecraft.world.item.Items.BUCKET)) ? null : CraftItemStack.asNMSCopy(event.getItemStack()) : ItemStack.EMPTY; // Paper - Fix PlayerBucketEmptyEvent result itemstack
             }
             // CraftBukkit end
             if (!flag2) {