FIXED - Schoolboy error.

Realised that the variable for QytContents List variable, which I was autogenerating/completing from IntelliJ was appending "List" to the name and I was again using IntelliJ's: code | generate | Setters & Getters to create them.

The 'field' name in the MongoDB was 'qtyContents' whilst I had

{{@ElementCollection
private List<QtyContents> qtyContentsList = new ArrayList<QtyContents>();}}

and

setQtyContentsList & getQtyContentsList

So the 'reflection' wasn't working.

Found it by creating a simple String array in Mongo of "Red,Blue & White" and trying to retrieve that.

Thanks for your patience and assistance. I'll continue to use OGM for my PoC.