I got the unchecked expression error when compiling and found the offending line to be 

```
ArrayList<Integer> items = (ArrayList<Integer>) this.items.clone();

```

I am trying to perform a deep copy of my object so I am cloning a property of the object and array list in the above manner. How can I fix this warning?

* I could use `@SuppressWarnings("unchecked")` but that is just hiding the problem (tho I expect none)
* If I clone manually by looping through all elements to it will be slower I think

Whats the correct way of doing this?