JPA Method
in javax.persistence.criteria.From

MapJoin<X,K,V> joinMap(
  String attributeName, 
  JoinType jt
)

Create a join to the specified Map-valued attribute using the given join type.
Parameters:
attributeName - name of the attribute for the target of the join
jt - join type
Return:
the resulting join
Throws:
IllegalArgumentException - if attribute of the given name does not exist
Since:
JPA 2.0