code: private function createRequest(TimeInTransitRequest $timeInTransitRequest)
      {
          $xml = new DOMDocument();
          $xml->formatOutput = true;
  
          $trackRequest = $xml->appendChild($xml->createElement('TimeInTransitRequest'));
          $trackRequest->setAttribute('xml:lang', 'en-US');
  
          $request = $trackRequest->appendChild($xml->createElement('Request'));
  
          $node = $xml->importNode($this->createTransactionNode(), true);
          $request->appendChild($node);
  
          $request->appendChild($xml->createElement('RequestAction', 'TimeInTransit'));
  
          $transitFromNode = $trackRequest->appendChild($xml->createElement('TransitFrom'));
          $address = $timeInTransitRequest->getTransitFrom();
          if (isset($address)) {
              $transitFromNode->appendChild($address->toNode($xml));
          }
  
          $transitToNode = $trackRequest->appendChild($xml->createElement('TransitTo'));
          $address = $timeInTransitRequest->getTransitTo();
          if (isset($address)) {
              $transitToNode->appendChild($address->toNode($xml));
          }
  
          $weight = $timeInTransitRequest->getShipmentWeight();
          if (isset($weight)) {
              $trackRequest->appendChild($weight->toNode($xml));
          }
  
          $packages = $timeInTransitRequest->getTotalPackagesInShipment();
          if (isset($packages)) {
              $trackRequest->appendChild($xml->createElement('TotalPackagesInShipment', $packages));
          }
  
          $invoiceLineTotal = $timeInTransitRequest->getInvoiceLineTotal();
          if (isset($invoiceLineTotal)) {
              $trackRequest->appendChild($invoiceLineTotal->toNode($xml));
          }
  
          $pickupDate = $timeInTransitRequest->getPickupDate();
          if ($pickupDate) {
              $trackRequest->appendChild($xml->createElement('PickupDate', $pickupDate->format('Ymd')));
          }
  
          $indicator = $timeInTransitRequest->getDocumentsOnlyIndicator();
          if ($indicator) {
              $trackRequest->appendChild($xml->createElement('DocumentsOnlyIndicator'));
          }
  
          return $xml->saveXML();
      }
docs: Create the TimeInTransit request.
  
  @param TimeInTransitRequest $timeInTransitRequest The request details. Refer to the UPS documentation for available structure
  
  @return string