/**
 * Implements hook_entity_presave().
 */
function {{ machine_name }}_entity_presave(Drupal\Core\Entity\EntityInterface $entity) {
  if ($entity instanceof ContentEntityInterface && $entity->isTranslatable()) {
    $route_match = \Drupal::routeMatch();
    \Drupal::service('content_translation.synchronizer')->synchronizeFields($entity, $entity->language()->getId(), $route_match->getParameter('source_langcode'));
  }
}