Paper/patches/server/0621-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 5510098be25ce06bc5f92eab2f83dc1086c4838f..578c3db52dda4c169b5ea615a4ce4a79f15a4cad 100644
--- a/src/main/java/net/minecraft/world/item/BucketItem.java
+++ b/src/main/java/net/minecraft/world/item/BucketItem.java
@@ -39,6 +39,8 @@ import org.bukkit.event.player.PlayerBucketFillEvent;
 
 public class BucketItem extends Item implements DispensibleContainerItem {
 
+    private static @Nullable ItemStack itemLeftInHandAfterPlayerBucketEmptyEvent = null; // Paper
+
     public final Fluid content;
 
     public BucketItem(Fluid fluid, Item.Properties settings) {
@@ -120,6 +122,13 @@ public class BucketItem extends Item implements DispensibleContainerItem {
     }
 
     public static ItemStack getEmptySuccessItem(ItemStack stack, Player player) {
+        // Paper start
+        if (itemLeftInHandAfterPlayerBucketEmptyEvent != null) {
+            ItemStack itemInHand = itemLeftInHandAfterPlayerBucketEmptyEvent;
+            itemLeftInHandAfterPlayerBucketEmptyEvent = null;
+            return itemInHand;
+        }
+        // Paper end
         return !player.getAbilities().instabuild ? new ItemStack(Items.BUCKET) : stack;
     }
 
@@ -150,6 +159,7 @@ 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 empty event result itemstack
             }
             // CraftBukkit end
             if (!flag1) {