CMR-Field abstract accessors have the same signatures as cmp-fields, except that single-valued relationships must return the local interface of the related entity, and multi-valued relationships can only return a java.util.Collection (or java.util.Set) object. For example, to declare a one-to-many relationship between organization and gangster, we declare the relationship from organization to gangster in the OrganizationBean class:

public abstract class OrganizationBean
    implements EntityBean 
{
    public abstract Set getMemberGangsters();
    public abstract void setMemberGangsters(Set gangsters);
} 

We also can declare the relationship from gangster to organization in the GangsterBean class:

public abstract class GangsterBean
    implements EntityBean 
{
    public abstract Organization getOrganization();
    public abstract void setOrganization(Organization org);
}

Although each bean declared a CMR field, only one of the two beans in a relationship must have a set of accessors. As with CMP fields, a CMR field is required to have both a getter and a setter method.