Pimcore\Model\Object\ClassDefinition\Data\Relations\AbstractRelations::rewriteIdsService PHP Method

    public function rewriteIdsService($data, $idMapping)
    {
        if (is_array($data)) {
            foreach ($data as &$element) {
                $id = $element->getId();
                $type = Element\Service::getElementType($element);
                if (array_key_exists($type, $idMapping) && array_key_exists($id, $idMapping[$type])) {
                    $element = Element\Service::getElementById($type, $idMapping[$type][$id]);
                }
            }
        }
        return $data;
    }