code: public function void($shipmentData)
      {
          if (is_array($shipmentData) && !isset($shipmentData['shipmentId'])) {
              throw new InvalidArgumentException('$shipmentData parameter is required to contain a key `shipmentId`.');
          }
  
          $request = $this->createVoidRequest($shipmentData);
          $this->response = $this->getRequest()->request($this->createAccess(), $request, $this->compileEndpointUrl($this->voidEndpoint));
          $response = $this->response->getResponse();
  
          if ($response->Response->ResponseStatusCode == 0) {
              throw new Exception(
                  "Failure ({$response->Response->Error->ErrorSeverity}): {$response->Response->Error->ErrorDescription}",
                  (int)$response->Response->Error->ErrorCode
              );
          } else {
              unset($response->Response);
  
              return $this->formatResponse($response);
          }
      }
docs: Void a shipping label / request.
  
  @param string|array $shipmentData Either the UPS Shipment Identification Number or an array of
  expanded shipment data [shipmentId:, trackingNumbers:[...]]
  
  @throws Exception
  
  @return \stdClass