Hibernate (Core {4.2.7.SP5-redhat-1}, using dialect PostgreSQL82Dialect) is generating a schema I don't understand, and it is failing when I think it shouldn't. The exception I'm getting is

    ERROR: ERROR: null value in column "aggregategroupmap_id" violates not-null constraint
      Detail: Failing row contains (1, 2, BILLPROGRESS, null, null).

Which is true since I didn't attempt to insert anything into the other column. I don't think I should have to because the columns refer to two different Maps.

This is my main MyClass class.

    import java.io.Serializable;
    import java.util.*;

    import javax.persistence.*;

    @SuppressWarnings("serial")
    @Entity public class MyClass implements Serializable {
        @Id @GeneratedValue private Long id;

        @OneToMany(cascade={CascadeType.ALL})
        private Map<String, GroupInfo> aggregateGroupMap;
        @OneToMany(cascade={CascadeType.ALL})
        private Map<String, GroupInfo> computationGroupMap;

        public MyClass() {
             aggregateGroupMap = new TreeMap<String, GroupInfo>();
             computationGroupMap = new TreeMap<String, GroupInfo>();
        }

        public Map<String, GroupInfo> getAggregateGroupMap() {
             return aggregateGroupMap;
        }
        public Map<String, GroupInfo> getComputationGroupMap() {
             return computationGroupMap;
        }

    }

This is a second class, referenced by the first class.

    import java.io.Serializable;
    import java.util.*;

    import javax.persistence.*;

    @SuppressWarnings("serial")
    @Entity public class GroupInfo implements Serializable {
        @Id @GeneratedValue private Long id;

        @ElementCollection
        @OrderColumn
        private List<String> groupLabels;
        @ElementCollection
        @OrderColumn
        private List<String> groupDescriptions;

        public GroupInfo() {
            groupLabels = new ArrayList<String>();
            groupDescriptions = new ArrayList<String>();
        }

        public List<String> getGroupLabels() {
            return groupLabels;
        }
        public List<String> getGroupDescriptions() {
            return groupDescriptions;
        }
    }

This class attempts to persist Objects:

    import java.util.*;

    import javax.persistence.*;

    public class TestIt {

        public static void main(String... args) throws Exception {
            EntityManagerFactory emf = Persistence.createEntityManagerFactory("JpaTest");
            EntityManager em = emf.createEntityManager();

            MyClass myClass = new MyClass();
            GroupInfo groupInfo = new GroupInfo();
            groupInfo.getGroupLabels().addAll(new ArrayList<String>(Arrays.asList(new String[] {"SKEWNESS"})));
            myClass.getComputationGroupMap().put("BILLPROGRESS", groupInfo);
 
            EntityTransaction tx = em.getTransaction();
            tx.begin();
            em.persist(myClass);
            tx.commit();
 
            em.close();
        }

    }

As far as I can tell, this is the problem table:

   create table MyClass_GroupInfo (

      MyClass_id int8 not null,

      computationGroupMap_id int8 not null,

      computationGroupMap_KEY varchar(255),

      aggregateGroupMap_id int8 not null,

     aggregateGroupMap_KEY varchar(255),

     primary key (MyClass_id, aggregateGroupMap_KEY)

  );

I tried adding @Column(nullable=true) but it didn't make any difference. Any suggestions?