/**
  * Returns what we known about the owner of a node
  *
  * @param Node $node
  *
  * @return null|array<string,int|string>
  */
 private function getOwnerData($node)
 {
     $owner = $node->getOwner();
     $ownerData = [];
     if ($owner) {
         $ownerData = ['uid' => $owner->getUID(), 'displayname' => $owner->getDisplayName()];
     }
     return $ownerData;
 }