[#SPIGOT-2787] "Cannot copy null stack" when iterating over recipes

Something goes wrong with validating item stacks when iterating over recipes. Using the following code:

Iterator<Recipe> it = plugin.getServer().recipeIterator();
            while (it.hasNext())
            {
                Recipe defaultRecipe = it.next();
                // intend to do something with this recipe, but the above line throws an Exception
           }

java.lang.IllegalArgumentException: Cannot copy null stack
	at org.apache.commons.lang.Validate.notNull(Validate.java:192) ~[spigot-1.11-R0.1-SNAPSHOT.jar:git-Spigot-d60de0a-d8c6364]
	at org.bukkit.inventory.ItemStack.<init>(ItemStack.java:135) ~[spigot-1.11-R0.1-SNAPSHOT.jar:git-Spigot-d60de0a-d8c6364]
	at org.bukkit.inventory.ShapelessRecipe.<init>(ShapelessRecipe.java:34) ~[spigot-1.11-R0.1-SNAPSHOT.jar:git-Spigot-d60de0a-d8c6364]
	at org.bukkit.craftbukkit.v1_11_R1.inventory.CraftShapelessRecipe.<init>(CraftShapelessRecipe.java:17) ~[spigot-1.11-R0.1-SNAPSHOT.jar:git-Spigot-d60de0a-d8c6364]
	at org.bukkit.craftbukkit.v1_11_R1.inventory.CraftShapelessRecipe.<init>(CraftShapelessRecipe.java:21) ~[spigot-1.11-R0.1-SNAPSHOT.jar:git-Spigot-d60de0a-d8c6364]
	at net.minecraft.server.v1_11_R1.ShapelessRecipes.toBukkitRecipe(ShapelessRecipes.java:27) ~[spigot-1.11-R0.1-SNAPSHOT.jar:git-Spigot-d60de0a-d8c6364]
	at net.minecraft.server.v1_11_R1.ShapelessRecipes.toBukkitRecipe(ShapelessRecipes.java:1) ~[spigot-1.11-R0.1-SNAPSHOT.jar:git-Spigot-d60de0a-d8c6364]
	at org.bukkit.craftbukkit.v1_11_R1.inventory.RecipeIterator.next(RecipeIterator.java:30) ~[spigot-1.11-R0.1-SNAPSHOT.jar:git-Spigot-d60de0a-d8c6364]
	at org.bukkit.craftbukkit.v1_11_R1.inventory.RecipeIterator.next(RecipeIterator.java:1) ~[spigot-1.11-R0.1-SNAPSHOT.jar:git-Spigot-d60de0a-d8c6364]
... my code as above

This seems to be relatively new, I did not see the issue in git-Spigot-d60de0a-a951a88

[SPIGOT-2787] "Cannot copy null stack" when iterating over recipes Created: 17/Nov/16 Updated: 18/Nov/16 Resolved: 18/Nov/16
Status:	Resolved
Project:	Spigot
Component/s:	None
Affects Version/s:	None
Fix Version/s:	None

[SPIGOT-2787] "Cannot copy null stack" when iterating over recipes Created: 17/Nov/16 Updated: 18/Nov/16 Resolved: 18/Nov/16