code: public function getUniqueId()
      {
          return $this->module ? ltrim($this->module->getUniqueId() . '/' . $this->id, '/') : $this->id;
      }
docs: Returns an ID that uniquely identifies this module among all modules within the current application.
  Note that if the module is an application, an empty string will be returned.
  @return string the unique ID of the module.