Added support for clone into the persistant collection
I think this is not enough. Its probably safer to initialize the collection. Then copy the array collection.
The real world problem that I was trying to solve was that manipulating the collection in a cloned instance also manipulated the collection in the original instance.
I was trying to solve this with the simplest method possible, is there a reason for making this more complex / resource hungry and initializing the collection?
Fixed in 93f79d0 and merged into 2.2 and 2.1.x