/**
  * Remove node fields that can only be written by an admin user.
  *
  * @param \Drupal\node\NodeInterface $node
  *   The node to remove fields where non-administrative users cannot write.
  *
  * @return \Drupal\node\NodeInterface
  *   The node with removed fields.
  */
 protected function removeNodeFieldsForNonAdminUsers(NodeInterface $node)
 {
     $node->set('status', NULL);
     $node->set('created', NULL);
     $node->set('changed', NULL);
     $node->set('promote', NULL);
     $node->set('sticky', NULL);
     $node->set('revision_timestamp', NULL);
     $node->set('revision_log', NULL);
     $node->set('uid', NULL);
     return $node;
 }