Paper/paper-server/nms-patches/net/minecraft/world/item/ItemBucket.patch

--- a/net/minecraft/world/item/ItemBucket.java
+++ b/net/minecraft/world/item/ItemBucket.java
@@ -29,6 +29,16 @@
 import net.minecraft.world.phys.MovingObjectPosition;
 import net.minecraft.world.phys.MovingObjectPositionBlock;
 
+// CraftBukkit start
+import net.minecraft.network.protocol.game.PacketPlayOutBlockChange;
+import net.minecraft.server.level.WorldServer;
+import org.bukkit.craftbukkit.event.CraftEventFactory;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.util.DummyGeneratorAccess;
+import org.bukkit.event.player.PlayerBucketEmptyEvent;
+import org.bukkit.event.player.PlayerBucketFillEvent;
+// CraftBukkit end
+
 public class ItemBucket extends Item {
 
     public final FluidType fluidType;
@@ -59,12 +69,22 @@
                 if (this.fluidType == FluidTypes.EMPTY) {
                     iblockdata = world.getType(blockposition);
                     if (iblockdata.getBlock() instanceof IFluidSource) {
+                        // CraftBukkit start
+                        FluidType dummyFluid = ((IFluidSource) iblockdata.getBlock()).removeFluid(DummyGeneratorAccess.INSTANCE, blockposition, iblockdata);
+                        PlayerBucketFillEvent event = CraftEventFactory.callPlayerBucketFillEvent((WorldServer) world, entityhuman, blockposition, blockposition, movingobjectpositionblock.getDirection(), itemstack, dummyFluid.a());
+
+                        if (event.isCancelled()) {
+                            ((EntityPlayer) entityhuman).playerConnection.sendPacket(new PacketPlayOutBlockChange(world, blockposition)); // SPIGOT-5163 (see PlayerInteractManager)
+                            ((EntityPlayer) entityhuman).getBukkitEntity().updateInventory(); // SPIGOT-4541
+                            return InteractionResultWrapper.fail(itemstack);
+                        }
+                        // CraftBukkit end
                         FluidType fluidtype = ((IFluidSource) iblockdata.getBlock()).removeFluid(world, blockposition, iblockdata);
 
                         if (fluidtype != FluidTypes.EMPTY) {
                             entityhuman.b(StatisticList.ITEM_USED.b(this));
                             entityhuman.playSound(fluidtype.a((Tag) TagsFluid.LAVA) ? SoundEffects.ITEM_BUCKET_FILL_LAVA : SoundEffects.ITEM_BUCKET_FILL, 1.0F, 1.0F);
-                            ItemStack itemstack1 = ItemLiquidUtil.a(itemstack, entityhuman, new ItemStack(fluidtype.a()));
+                            ItemStack itemstack1 = ItemLiquidUtil.a(itemstack, entityhuman, CraftItemStack.asNMSCopy(event.getItemStack())); // CraftBukkit
 
                             if (!world.isClientSide) {
                                 CriterionTriggers.j.a((EntityPlayer) entityhuman, new ItemStack(fluidtype.a()));
@@ -79,7 +99,7 @@
                     iblockdata = world.getType(blockposition);
                     BlockPosition blockposition2 = iblockdata.getBlock() instanceof IFluidContainer && this.fluidType == FluidTypes.WATER ? blockposition : blockposition1;
 
-                    if (this.a(entityhuman, world, blockposition2, movingobjectpositionblock1)) {
+                    if (this.a(entityhuman, world, blockposition2, movingobjectpositionblock1, movingobjectpositionblock1.getDirection(), blockposition, itemstack)) { // CraftBukkit
                         this.a(world, itemstack, blockposition2);
                         if (entityhuman instanceof EntityPlayer) {
                             CriterionTriggers.y.a((EntityPlayer) entityhuman, blockposition2, itemstack);
@@ -104,6 +124,11 @@
     public void a(World world, ItemStack itemstack, BlockPosition blockposition) {}
 
     public boolean a(@Nullable EntityHuman entityhuman, World world, BlockPosition blockposition, @Nullable MovingObjectPositionBlock movingobjectpositionblock) {
+        return a(entityhuman, world, blockposition, movingobjectpositionblock, null, null, null);
+    }
+
+    public boolean a(EntityHuman entityhuman, World world, BlockPosition blockposition, @Nullable MovingObjectPositionBlock movingobjectpositionblock, EnumDirection enumdirection, BlockPosition clicked, ItemStack itemstack) {
+        // CraftBukkit end
         if (!(this.fluidType instanceof FluidTypeFlowing)) {
             return false;
         } else {
@@ -113,8 +138,18 @@
             boolean flag = iblockdata.a(this.fluidType);
             boolean flag1 = iblockdata.isAir() || flag || block instanceof IFluidContainer && ((IFluidContainer) block).canPlace(world, blockposition, iblockdata, this.fluidType);
 
+            // CraftBukkit start
+            if (flag1 && entityhuman != null) {
+                PlayerBucketEmptyEvent event = CraftEventFactory.callPlayerBucketEmptyEvent((WorldServer) world, entityhuman, blockposition, clicked, enumdirection, itemstack);
+                if (event.isCancelled()) {
+                    ((EntityPlayer) entityhuman).playerConnection.sendPacket(new PacketPlayOutBlockChange(world, blockposition)); // SPIGOT-4238: needed when looking through entity
+                    ((EntityPlayer) entityhuman).getBukkitEntity().updateInventory(); // SPIGOT-4541
+                    return false;
+                }
+            }
+            // CraftBukkit end
             if (!flag1) {
-                return movingobjectpositionblock != null && this.a(entityhuman, world, movingobjectpositionblock.getBlockPosition().shift(movingobjectpositionblock.getDirection()), (MovingObjectPositionBlock) null);
+                return movingobjectpositionblock != null && this.a(entityhuman, world, movingobjectpositionblock.getBlockPosition().shift(movingobjectpositionblock.getDirection()), (MovingObjectPositionBlock) null, enumdirection, clicked, itemstack); // CraftBukkit
             } else if (world.getDimensionManager().isNether() && this.fluidType.a((Tag) TagsFluid.WATER)) {
                 int i = blockposition.getX();
                 int j = blockposition.getY();