code: public function setMapper(MapperInterface $mapper)
      {
          if (!$mapper instanceof UserMapperInterface) {
              throw new \InvalidArgumentException(sprintf(
                  'First argument must implement CmsUser\Persistence\UserMapperInterface; %s given',
                  is_object($mapper) ? get_class($mapper) : gettype($mapper)
              ));
          }
  
          return parent::setMapper($mapper);
      }
docs: {@inheritDoc}