code: private function _convertListFinancialEventGroups($request) {
  
          $parameters = array();
          $parameters['Action'] = 'ListFinancialEventGroups';
          if ($request->isSetSellerId()) {
              $parameters['SellerId'] =  $request->getSellerId();
          }
          if ($request->isSetMWSAuthToken()) {
              $parameters['MWSAuthToken'] =  $request->getMWSAuthToken();
          }
          if ($request->isSetMaxResultsPerPage()) {
              $parameters['MaxResultsPerPage'] =  $request->getMaxResultsPerPage();
          }
          if ($request->isSetFinancialEventGroupStartedAfter()) {
              $parameters['FinancialEventGroupStartedAfter'] =  $request->getFinancialEventGroupStartedAfter();
          }
          if ($request->isSetFinancialEventGroupStartedBefore()) {
              $parameters['FinancialEventGroupStartedBefore'] =  $request->getFinancialEventGroupStartedBefore();
          }
  
          return $parameters;
      }
docs: Convert ListFinancialEventGroupsRequest to name value pairs