Exception in thread "main" org.hibernate.MappingException: Could not determine type for: java.util.Set, at table: Area, for columns: [org.hibernate.mapping.Column(belongsTo)]
   at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:269)
   at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:253)
   at org.hibernate.mapping.Property.isValid(Property.java:185)
   at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:435)
   at org.hibernate.mapping.JoinedSubclass.validate(JoinedSubclass.java:40)
   at org.hibernate.cfg.Configuration.validate(Configuration.java:1112)
   at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1297)
   at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:854)
   at de.iac_leipzig.alkis.persistence.HibernateInheritanceTest.main(HibernateInheritanceTest.java:66)

@MappedSuperclass
public abstract class Versioned implements JDBCPersistable {
   
    @Embeddable
    public static class VersionedPK implements Serializable {

        private static final long serialVersionUID = 1L;

        protected String guid = GUIDGenerator.newGUID();

        protected String branch_ID;

        protected Date valid_from;

        @Override
        public String toString() {
            return guid + branch_ID + valid_from.toString();
        }


        public String getBranch_ID() {
            return branch_ID;
        }


        void setBranch_ID( String branch_ID ) {
            this.branch_ID = branch_ID;
        }


        public Date getValid_from() {
            return valid_from;
        }


        public void setValid_from( Date valid_from ) {
            this.valid_from = valid_from;
        }


        public boolean equals( Object o ) {
            if (this == o)
                return true;
            if (o == null || getClass() != o.getClass())
                return false;

            VersionedPK that = (VersionedPK) o;

            if (valid_from != null ? !valid_from.equals( that.valid_from )
                    : that.valid_from != null)
                return false;
            if (branch_ID != null ? !branch_ID.equals( that.branch_ID )
                    : that.branch_ID != null)
                return false;
            if (this.guid != null ? !this.guid.equals( that.guid )
                    : that.guid != null)
                return false;

            return true;
        }


        public int hashCode() {
            int result;
            result = (valid_from != null ? valid_from.hashCode() : 0);
            result = 31 * result
                    + (branch_ID != null ? branch_ID.hashCode() : 0);
            result = 17 * result + (guid != null ? guid.hashCode() : 0);
            return result;
        }

    }

    public static final String PROP_ID = "id";
   
    @EmbeddedId
    VersionedPK id = new VersionedPK();

    @Transient
    public String getId() {
        return id.toString();
    }
   
    public void setId( VersionedPK id ) {
        this.id = id;
    }
   
    public void setId( String id ) {
        this.id.guid = id;
    }

    private Date valid_until;

    private String author_from;

    private String author_until;
   
    private String externalId = null;


    public Date getValid_until() {
        return valid_until;
    }


    public void setValid_until( Date valid_until ) {
        this.valid_until = valid_until;
    }


    public String getAuthor_from() {
        return author_from;
    }


    public void setAuthor_from( String author_from ) {
        this.author_from = author_from;
    }


    public String getAuthor_until() {
        return author_until;
    }


    public void setAuthor_until( String author_until ) {
        this.author_until = author_until;
    }


    public void insert( JDBCPersister persister ) throws Exception {
    }


    public String getExternalId() {
        return externalId;
    }


    public void setExternalId( String externalId ) {
        this.externalId = externalId;
    }
}

@Entity
public class Area

extends Versioned

implements java.io.Serializable

{

   private static final long serialVersionUID = 1L;

   public static final String PROP_BELONGS_TO = "belongsTo";

   private java.util.Set<Area> belongsTo = new java.util.HashSet<Area>();

   @ManyToMany(fetch = FetchType.LAZY)
   @JoinTable(name = "Area_belongsTo")
   public java.util.Set<Area> getBelongsTo() {
      return belongsTo;
   }


   public void setBelongsTo(
         java.util.Set<Area> belongsTo) {
      this.belongsTo = belongsTo;
   }

   @ManyToMany(fetch = FetchType.LAZY)
   @JoinTable(
           name = "Area_belongsTo",
            joinColumns={
                @JoinColumn(name="versionedArea1Id", referencedColumnName = "GUID"),
                @JoinColumn(name="versionedArea1BranchId", referencedColumnName = "BRANCH_ID"),
                @JoinColumn(name="versionedArea1ValidFrom", referencedColumnName = "VALID_FROM")
           },
           inverseJoinColumns={
                   @JoinColumn(name="versionedArea2Id", referencedColumnName = "GUID"),
                   @JoinColumn(name="versionedArea2BranchId", referencedColumnName = "BRANCH_ID"),
                   @JoinColumn(name="versionedArea2ValidFrom", referencedColumnName = "VALID_FROM")
           }
   )

@Entity
public class Area

extends Versioned

implements java.io.Serializable

{

   private static final long serialVersionUID = 1L;

   public static final String PROP_BELONGS_TO = "belongsTo";

   @ManyToMany(fetch = FetchType.LAZY)
   @JoinTable(name = "Area_belongsTo")
   private java.util.Set<Area> belongsTo = new java.util.HashSet<Area>();

   public java.util.Set<Area> getBelongsTo() {
      return belongsTo;
   }


   public void setBelongsTo(
         java.util.Set<Area> belongsTo) {
      this.belongsTo = belongsTo;
   }