code: public function getBillOfLading($request)
      {
          if (!($request instanceof FBAInboundServiceMWS_Model_GetBillOfLadingRequest)) {
              $request = new FBAInboundServiceMWS_Model_GetBillOfLadingRequest($request);
          }
          $parameters = $request->toQueryParameterArray();
          $parameters['Action'] = 'GetBillOfLading';
          $httpResponse = $this->_invoke($parameters);
  
          $response = FBAInboundServiceMWS_Model_GetBillOfLadingResponse::fromXML($httpResponse['ResponseBody']);
          $response->setResponseHeaderMetadata($httpResponse['ResponseHeaderMetadata']);
          return $response;
      }
docs: Get Bill Of Lading
  Retrieves the PDF-formatted BOL data for a partnered LTL shipment.
  This PDF data will be ZIP'd and then it will be encoded as a Base64 string, and a
  MD5 hash is included with the response to validate the BOL data which will be encoded as Base64.
  
  @param mixed $request array of parameters for FBAInboundServiceMWS_Model_GetBillOfLading request or FBAInboundServiceMWS_Model_GetBillOfLading object itself
  @see FBAInboundServiceMWS_Model_GetBillOfLadingRequest
  @return FBAInboundServiceMWS_Model_GetBillOfLadingResponse
  
  @throws FBAInboundServiceMWS_Exception