addToolbarItemsToMatchHtmlElementsInFormat example

      // have valid settings.       // For all already enabled plugins, find the ones that are configurable,       // and add their default settings. For enabled plugins with element       // subsets, compute the appropriate settings to achieve the subset that       // matches the original text format restrictions.       $this->addDefaultSettingsForEnabledConfigurablePlugins($editor);
      $this->computeSubsetSettingForEnabledPluginsWithSubsets($editor, $text_format);
    }

    // Add toolbar items based on HTML tags and attributes.     // NOTE: Helper updates $editor->settings by reference and returns info for the message.     $result = $this->addToolbarItemsToMatchHtmlElementsInFormat($text_format, $editor);
    if ($result !== NULL) {
      [$enabling_message_content, $enabled_for_attributes_message_content, $missing, $plugins_enabled] = $result;

      // Distinguish between unsupported elements covering only tags or not.       $missing_attributes = new HTMLRestrictions(array_filter($missing->getAllowedElements()));
      $unsupported = $missing->diff($missing_attributes);

      if ($enabling_message_content) {
        $this->logger->info('The CKEditor 5 migration enabled the following plugins to support tags that are allowed by the %text_format text format: %enabling_message_content. The text format must be saved to make these changes active.',
          [
            '%text_format' => $editor->getFilterFormat()->get('name'),