code: public function getPackageTrackingDetails($request)
      {
          if (!($request instanceof FBAOutboundServiceMWS_Model_GetPackageTrackingDetailsRequest)) {
              $request = new FBAOutboundServiceMWS_Model_GetPackageTrackingDetailsRequest($request);
          }
          $parameters = $request->toQueryParameterArray();
          $parameters['Action'] = 'GetPackageTrackingDetails';
          $httpResponse = $this->_invoke($parameters);
  
          $response = FBAOutboundServiceMWS_Model_GetPackageTrackingDetailsResponse::fromXML($httpResponse['ResponseBody']);
          $response->setResponseHeaderMetadata($httpResponse['ResponseHeaderMetadata']);
          return $response;
      }
docs: Get Package Tracking Details
  Gets the tracking details for a shipment package.
  
  @param mixed $request array of parameters for FBAOutboundServiceMWS_Model_GetPackageTrackingDetails request or FBAOutboundServiceMWS_Model_GetPackageTrackingDetails object itself
  @see FBAOutboundServiceMWS_Model_GetPackageTrackingDetailsRequest
  @return FBAOutboundServiceMWS_Model_GetPackageTrackingDetailsResponse
  
  @throws FBAOutboundServiceMWS_Exception