Hi, I have problem figure out a good way to make NHibernate transparent and be able to initialize ISet properties of entities.

For example, if I have a Customer entity which has a property Orders of type ISet.
I would like to separate the entities from the business logic projects.
This way the entities can be reused and the entities project does not reference NHibernate libraries.
Now, I need to initialize the Orders property of the customer but I do not have reference to Iesi collections, and if I do have reference then NHibernate is not transparent (not entirely).

Please advise,
Ido.