code: protected static function loadCorpNegoFare($corporateNegoFare)
      {
          $opt = [];
  
          if ($corporateNegoFare !== null) {
              $po = new PricingOptionGroup(PricingOptionKey::OPTION_CORPORATE_NEGOTIATED_FARES);
  
              $po->optionDetail = new OptionDetail($corporateNegoFare);
  
              $opt[] = $po;
          }
  
          return $opt;
      }
docs: Load corporate negofare
  
  @param string|null $corporateNegoFare
  @return PricingOptionGroup[]