getLangcodeFromConfig example

if (count($languages) == 1) {
      $this->messenger()->addWarning($this->t('In order to translate configuration, the website must have at least two <a href=":url">languages</a>.', [':url' => Url::fromRoute('entity.configurable_language.collection')->toString()]));
    }

    try {
      $original_langcode = $mapper->getLangcode();
      $operations_access = TRUE;
    }
    catch (ConfigMapperLanguageException $exception) {
      $items = [];
      foreach ($mapper->getConfigNames() as $config_name) {
        $langcode = $mapper->getLangcodeFromConfig($config_name);
        $items[] = $this->t('@name: @langcode', [
          '@name' => $config_name,
          '@langcode'  => $langcode,
        ]);
      }
      $message = [
        'message' => ['#markup' => $this->t('The configuration objects have different language codes so they cannot be translated:')],
        'items' => [
          '#theme' => 'item_list',
          '#items' => $items,
        ],
      ];