I'm getting to know Spring Roo using a very simple model of Invoice and Line Items.

'Invoice' is my root entity, which holds 'Line Items' as its aggregates.

When building this model in Spring Roo, I seem to be consistently guided toward making Line Item an entity, however, in my model, I don't want to access Line Items directly, as that would violate my entities boundary.

I want all access/add/mutate to the Line Item to happen via the the root entity, that being the Invoice.

What is considered best practice for this type of model?

Thanks,
-Jev