code: private function convertSubmitFeed($request)
      {
  
          $parameters = array();
          $parameters['Action'] = 'SubmitFeed';
          if ($request->isSetMarketplace()) {
              $parameters['Marketplace'] = $request->getMarketplace();
          }
          if ($request->isSetMerchant()) {
              $parameters['Merchant'] = $request->getMerchant();
          }
          if ($request->isSetMarketplaceIdList()) {
              $marketplaceIdList = $request->getMarketplaceIdList();
              foreach ($marketplaceIdList->getId() as $idIndex => $id) {
                  $parameters['MarketplaceIdList.Id.' . ($idIndex + 1)] = $id;
              }
          }
          if ($request->isSetFeedType()) {
              $parameters['FeedType'] = $request->getFeedType();
          }
          if ($request->isSetPurgeAndReplace()) {
              $parameters['PurgeAndReplace'] = $request->getPurgeAndReplace() ? "true" : "false";
          }
          if ($request->isSetMWSAuthToken()) {
              $parameters['MWSAuthToken'] = $request->getMWSAuthToken();
          }
  
          $headers = array();
          array_push($headers, "Content-Type: " . $request->getContentType()->toString());
  
          return array(CONVERTED_PARAMETERS_KEY => $parameters, CONVERTED_HEADERS_KEY => $headers);
      }
docs: Convert SubmitFeedRequest to name value pairs
  @param MarketplaceWebService_Model_SubmitFeedRequest $request
  @return array