The @BasicMap annotation is mainly for when both the key and value are
Basic. However JPA 2.0 will have just extended Map support. If you use
the latest EclipseLink 2.0 build there should be some level of support for
the new @MapKeyClass, @MapKeyJoinColumn JPA 2.0 annotations.
Otherwise in EclipseLink 1.1 / JPA 1.0, you could map the relation table
as an Entity which contains the OneToOne to the key and the Basic value.