code: public function loadUserByUsername($username)
      {
          $json = FilesystemTools::readFile(sprintf('%s/users/users.json', $this->configurationHandler->siteDir()));
          $users = json_decode($json, true);
  
          if (array_key_exists($username, $users)) {
              $userData = $users[$username];
  
              return new User($username, $userData["password"], $userData["salt"], $userData["roles"]);
          }
  
          throw new UsernameNotFoundException(
              sprintf('Username "%s" does not exist.', $username)
          );
      }
docs: {@inheritdoc}