JPA Container Filter

I have JPA Cointainer that I am using to create combo box (but I need to filter only certain rows), problem is that table that JPA Container is related to has composite primary key. When I try to filter values in container based on field value in composite primary key I had to get list of all composite primary keys and add filter per each key to main class. I need to bind that combobox to persistent member. What is best approach?