Inheritance: extends eZ\Publish\Core\REST\Server\Controller
 /**
  * If the published content is a user, return directly without publishing.
  *
  * @param mixed $contentId
  * @param int $versionNumber
  *
  * @return \eZ\Publish\Core\REST\Server\Values\NoContent
  */
 public function publishVersion($contentId, $versionNumber)
 {
     if (!$this->isUserContent($contentId)) {
         parent::publishVersion($contentId, $versionNumber);
     }
     return new NoContent();
 }