code: public function normalize($group, $format = null, array $context = [])
      {
          if ($format === 'csv' && $this->contextHasGroup('TableExport', $context)) {
              return (string)$group;
          }
  
          return parent::normalize($group, $format, $context);
      }
docs: @inheritdoc
  
  @param CustomerGroupInterface $group