code: private function extractUserRights(TokenInterface $token)
      {
          $beUser = $token->getUser();
          if (!($beUser instanceof BackendUser)) {
              return [];
          }
  
          $allowedModules = $beUser->modules;
          switch (true) {
              case \is_string($allowedModules):
                  $allowedModules = unserialize($allowedModules, ['allowed_classes' => false]);
                  break;
              case null === $allowedModules:
                  $allowedModules = [];
                  break;
              default:
          }
          return array_flip($allowedModules);
      }
docs: Extract the permissions from the Contao backend user.
  
  @param TokenInterface $token The token.
  
  @return array