code: public function fetchUserName(SecurityContextInterface $security, ConfigurationHandler $configurationHandler)
      {
          $user = $this->fetchUser($security, $configurationHandler);
          if (null === $user) {
              return $user;
          }
  
          return $user->getUsername();
      }
docs: Returns the current name for the signed in user
  @param \Symfony\Component\Security\Core\SecurityContextInterface $security
  @param \RedKiteCms\Configuration\ConfigurationHandler $configurationHandler
  
  @return string