code: protected function mergeOptions($existingOptions, $newOptions)
      {
          if (!empty($newOptions)) {
              $existingOptions = array_merge(
                  $existingOptions,
                  $newOptions
              );
          }
  
          return $existingOptions;
      }
docs: Merges Pricing options
  
  @param PricingOption[] $existingOptions
  @param PricingOption[] $newOptions
  @return PricingOption[] merged array