<property name="requiredResources" type="ResourcesUserType" column="resourceNames" />

<set name="requiredResources" cascade="save-update" table="RESOURCE">
   <key column="RESOURCE_ID" />
   <one-to-many class="Resource" />
</set>

public class ResourcesUserType implements UserType {

   @Override
   public Object assemble(Serializable arg0, Object arg1)
         throws HibernateException {
      return arg0;
   }

   @Override
   public Object deepCopy(Object arg0) throws HibernateException {
      return arg0;
   }

   @Override
   public Serializable disassemble(Object arg0) throws HibernateException {
      return (Serializable)arg0;
   }

   @Override
   public boolean equals(Object x, Object y) throws HibernateException {
      return (x == null) ? (y == null) : x.equals(y);
   }

   @Override
   public int hashCode(Object arg0) throws HibernateException {
      return ((Resource)arg0).hashCode();
   }

   @Override
   public boolean isMutable() {
      return false;
   }

   @Override
   public Object nullSafeGet(ResultSet rs, String[] names, Object owner)
         throws HibernateException, SQLException {
      String rResources = (String)Hibernate.STRING.nullSafeGet(rs, names[0]);//rs.getNString("resourceNames");
     
      ArrayList<Resource> returnedResources = new ArrayList<Resource>();
     
      for (String r : rResources.split(",")){
         Resource resource = new Resource();
         resource.setName(r.trim());
         returnedResources.add(resource);
      }     
      return returnedResources.toArray();
   }

   @SuppressWarnings("unchecked")
   @Override
   public void nullSafeSet(PreparedStatement st, Object value, int index)
         throws HibernateException, SQLException {
     
      /*DEBUG*/System.out.println("Object Value: "+value);
     
      if (value == null)
         throw new IllegalArgumentException( "Received object in nullSafeSet was null - " + returnedClass() );

      if (!(value instanceof Set
            && (((Set)value).iterator().next()) instanceof Resource)){
         throw new IllegalArgumentException( "Received object in nullSafeSet was " + value.getClass().getName() + " in " + returnedClass() );
      }
           
      String resources="";
      if (value == null) {
         st.setString(index, "");
       } else {
          //Build the comma separated lists for database
             for (Resource r : (Set<Resource>)value){//if this is not a set of resources, the exception would have been thrown already
                resources+=r.getName()+",";
             }
          //remove the additional comma
             resources=resources.substring(0,(resources.length()-1));
       }
      Hibernate.STRING.nullSafeSet(st, resources, index);
   }

   @Override
   public Object replace(Object arg0, Object arg1, Object arg2)
         throws HibernateException {
      return arg0;
   }

   @Override
   public Class returnedClass() {
      return Resource[].class;
   }

   @Override
   public int[] sqlTypes() {
      return new int[] {Hibernate.STRING.sqlType()};
   }

}