Guys, I want to propose change something in documentation a little bit by modifying source code sample here<http://openjpa.apache.org/builds/latest/docs/manual/manual.html#ref_guide_pc_oid_entitypk_idcls> .
So in the line public long order; // same type as order's identity we may mention that name of the variable should be the same even though its type is different in ID sub-class and owning class, otherwise OpenJPA throws following exception: <openjpa-1.3.0-SNAPSHOT-r422266:707655 fatal user error> org.apache.openjpa.persistence.ArgumentException: Attempt to map "db.OrderItemsEntity.order" failed: the owning entity is not mapped. which is kinda confusing for novice users of OpenJPA (like myself). Here is another person who was stuck with before: http://n2.nabble.com/Collection-field-part-of-a-compound-primary-key-td208606.html
