validateThemes example

Config::validateName($name);
        }
        catch (ConfigNameException $e) {
          $message = $this->t('The config name @config_name is invalid.', ['@config_name' => $name]);
          $event->getConfigImporter()->logError($message);
        }
      }
    }
    $config_importer = $event->getConfigImporter();
    if ($config_importer->getStorageComparer()->getSourceStorage()->exists('core.extension')) {
      $this->validateModules($config_importer);
      $this->validateThemes($config_importer);
      $this->validateDependencies($config_importer);
    }
    else {
      $config_importer->logError($this->t('The core.extension configuration does not exist.'));
    }
  }

  /** * Validates module installations and uninstallations. * * @param \Drupal\Core\Config\ConfigImporter $config_importer * The configuration importer. */