code: public Iterator getIteratorByQuery(Query query) throws PersistenceBrokerException
      {
          Class itemClass = query.getSearchClass();
          ClassDescriptor cld = getClassDescriptor(itemClass);
          return getIteratorFromQuery(query, cld);
      }
docs: returns an Iterator that iterates Objects of class c if calling the .next()
  method. The Elements returned come from a SELECT ... WHERE Statement
  that is defined by the Query query.
  If itemProxy is null, no proxies are used.