Check for incorrect FluidBucketWrapper usage

Items that use FluidBucketWrapper incorrectly:
- Will not get filling recipes
- Cannot be filled with the spout

src/main/java/com/simibubi/create/compat/jei/category/SpoutCategory.java

@@ -12,6 +12,7 @@ import com.simibubi.create.AllBlocks;
 import com.simibubi.create.Create;
 import com.simibubi.create.compat.jei.category.animations.AnimatedSpout;
 import com.simibubi.create.content.contraptions.fluids.actors.FillingRecipe;
+import com.simibubi.create.content.contraptions.fluids.actors.GenericItemFilling;
 import com.simibubi.create.content.contraptions.fluids.potion.PotionFluidHandler;
 import com.simibubi.create.content.contraptions.processing.ProcessingRecipeBuilder;
 import com.simibubi.create.foundation.fluid.FluidIngredient;
@@ -71,6 +72,8 @@ public class SpoutCategory extends CreateRecipeCategory<FillingRecipe> {
 						ItemStack copy = stack.copy();
 						copy.getCapability(CapabilityFluidHandler.FLUID_HANDLER_ITEM_CAPABILITY)
 							.ifPresent(fhi -> {
+								if (!GenericItemFilling.isFluidHandlerValid(copy, fhi))
+									return;
 								FluidStack fluidCopy = fluidStack.copy();
 								fluidCopy.setAmount(1000);
 								fhi.fill(fluidCopy, FluidAction.EXECUTE);

src/main/java/com/simibubi/create/content/contraptions/fluids/actors/GenericItemFilling.java

@@ -5,9 +5,11 @@ import com.simibubi.create.content.contraptions.fluids.potion.PotionFluidHandler
 import com.simibubi.create.foundation.fluid.FluidHelper;
 
 import net.minecraft.fluid.Fluids;
+import net.minecraft.item.BucketItem;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 import net.minecraft.item.Items;
+import net.minecraft.item.MilkBucketItem;
 import net.minecraft.potion.PotionUtils;
 import net.minecraft.potion.Potions;
 import net.minecraft.world.World;
@@ -20,6 +22,33 @@ import net.minecraftforge.fluids.capability.wrappers.FluidBucketWrapper;
 
 public class GenericItemFilling {
 
+	/**
+	 * Checks if an ItemStack's IFluidHandlerItem is valid. Ideally, this check would
+	 * not be necessary. Unfortunately, some mods that copy the functionality of the
+	 * MilkBucketItem copy the FluidBucketWrapper capability that is patched in by
+	 * Forge without looking into what it actually does. In all cases this is
+	 * incorrect because having a non-bucket item turn into a bucket item does not
+	 * make sense.
+	 * 
+	 * <p>This check is only necessary for filling since a FluidBucketWrapper will be
+	 * empty if it is initialized with a non-bucket item.
+	 * 
+	 * @param stack The ItemStack.
+	 * @param fluidHandler The IFluidHandlerItem instance retrieved from the ItemStack.
+	 * @return If the IFluidHandlerItem is valid for the passed ItemStack.
+	 */
+	public static boolean isFluidHandlerValid(ItemStack stack, IFluidHandlerItem fluidHandler) {
+		// Not instanceof in case a correct subclass is made
+		if (fluidHandler.getClass() == FluidBucketWrapper.class) {
+			Item item = stack.getItem();
+			// Forge does not patch the FluidBucketWrapper onto subclasses of BucketItem
+			if (item.getClass() != BucketItem.class && !(item instanceof MilkBucketItem)) {
+				return false;
+			}
+		}
+		return true;
+	}
+
 	public static boolean canItemBeFilled(World world, ItemStack stack) {
 		if (stack.getItem() == Items.GLASS_BOTTLE)
 			return true;
@@ -31,6 +60,8 @@ public class GenericItemFilling {
 		IFluidHandlerItem tank = capability.orElse(null);
 		if (tank == null)
 			return false;
+		if (!isFluidHandlerValid(stack, tank))
+			return false;
 		for (int i = 0; i < tank.getTanks(); i++) {
 			if (tank.getFluidInTank(i)
 				.getAmount() < tank.getTankCapacity(i))