Unlimited, xp glitch/exploit.

Problem:

I am tired of my friends joining my world and using this unlimited XP glitch. It is unfair to me because it's my world and I play fair.

 

Reproduce:

First, you craft 2 book and Quills. Next, input whatever you want in the first Book and Quill and close/finish the book. Next, place both the finished book and the Book and Quill on a crafting table to combine them. Finally, keeping the final product in your inventory, place any enchanted item in a grindstone and repeatedly take the item out.

 

Product from bug:

This bug can duplicate tools, generate unlimited XP, and if follow the same steps using an anvil instead of a grindstone, you can duplicate enchanted tools/weapons/armor.