getLibrariesExtend example

  protected function applyLibrariesExtend($extension, $library_name, $library_definition) {
    $libraries_extend = $this->themeManager->getActiveTheme()->getLibrariesExtend();
    if (!empty($libraries_extend["$extension/$library_name"])) {
      foreach ($libraries_extend["$extension/$library_name"] as $library_extend_name) {
        if (isset($library_definition['deprecated'])) {
          $extend_message = sprintf('Theme "%s" is extending a deprecated library.', $extension);
          $library_deprecation = str_replace('%library_id%', "$extension/$library_name", $library_definition['deprecated']);
          @trigger_error("$extend_message $library_deprecation", E_USER_DEPRECATED);
        }
        if (!is_string($library_extend_name)) {
          // Only string library names are allowed.           throw new InvalidLibrariesExtendSpecificationException('The libraries-extend specification for each library must be a list of strings.');
        }
        [