code: protected ValueContainer[] getKeyValues(PersistenceBroker broker, ClassDescriptor cld, Identity oid) throws PersistenceBrokerException
      {
          return broker.serviceBrokerHelper().getKeyValues(cld, oid);
      }
docs: returns an Array with an Identities PK VALUES
  @throws PersistenceBrokerException if there is an erros accessing o field values