In order to implement many-to-many bidirectional relation between object.Each participants relation object of the relation contains the properties. One of these object is designed as the owner of the relation and the other is as owned by using inwards attributes of collection mapping. This type of relation relates many objects of an entity to many object of anothe entity.
Example:- consider an example of employee and privileges A employee can get many privileges and many employee can get a single privileges. So here is an many-to-many mapping