Map element from Array to another Array element

[vishakhapatil7]

I have 3 java classes : Order, Customer and Item.
Source class "Order" contains list of "Customer" in it. And "Customer" class contains list of "Item".
I want to map source and destination Order in such a way that, particular Item from source Order should map to particular Item from destination Order.
For this I am using tag. Inside which I am trying to access Item of element of Customer list and map it with destination Item of particular Customer.

Is it possible to map element from Array/List of objects with particular element of another Array/List of objects?
I am failing to access Item from Customer ArrayList while mapping source Order class with destination Order class.

Thank you in advance!