code: public function createService(ServiceLocatorInterface $serviceLocator)
      {
          $options = $serviceLocator->get('HtSettingsModule\Options\ModuleOptions');
          $mapper = new DbSettingsMapper();
          $mapper->setDbAdapter($serviceLocator->get('HtSettingsModule\DbAdapter'));
          $entityClass = $options->getParameterEntityClass();
          $mapper->setEntityPrototype(new $entityClass);
          $mapper->setTableName($options->getSettingsTable());
  
          return $mapper;
      }
docs: Gets settings mapper
  
  @param  ServiceLocatorInterface $serviceLocator
  @return DbSettingsMapper