getTranslationFilesPattern example

  public function findTranslationFiles($langcode = NULL) {
    $files = [];
    if (is_dir($this->directory)) {
      $files = $this->fileSystem->scanDirectory($this->directory, $this->getTranslationFilesPattern($langcode), ['recurse' => FALSE]);
    }
    return $files;
  }

  /** * Provides translation file name pattern. * * @param string $langcode * (optional) The language code corresponding to the language for which we * want to find translation files. * * @return string * String file pattern. */