code: public void registerCommands(Iterable<Class<? extends RESTCallback>> cmdClasses,
                                   StorageService service,
                                   StorageService parentService) {
          m_cmdRegistry.setParent(service.getClass().getSimpleName(), parentService.getClass().getSimpleName());
          m_cmdRegistry.registerCallbacks(service, cmdClasses);
      }
docs: Register a set of application REST commands as belonging to the given storage
  service owner, which extends another storage service. The commands are defined
  via a set of {@link RESTCallback} objects, which must use the {@link Description}
  annotation to provide metadata about the commands.
  
  @param callbackClasses   Iterable collection of {@link RESTCallback} classes
  that define application-specific REST commands to be
  registered.
  @param service           {@link StorageService} that owns the commands.
  @param parentService     {@link StorageService} whose commands are extended and/or
  overridden by the given service's new commands.