Implement dependency injection for configs.

namespace Drupal\opensearchtab\Controller;

use Drupal\Core\Config\ConfigFactoryInterface;

use Drupal\Core\Config\ImmutableConfig;

use Drupal\Core\Controller\ControllerBase;

use Symfony\Component\DependencyInjection\ContainerInterface;

use Symfony\Component\HttpFoundation\Response;

/**

 * OpenSearchDescriptionController .

 */

class OpenSearchDescriptionController {

class OpenSearchDescriptionController extends ControllerBase {

  /**

   * @var ImmutableConfig $system_config

   */

  private $system_config;

  /**

   * @var ImmutableConfig $ost_config

   */

  private $ost_config;

  /**

   * Class constructor.

   *

   * @param ConfigFactoryInterface $config_factory

   *   The config factory service.

   */

  public function __construct(ConfigFactoryInterface $config_factory) {

    $this->system_config = $config_factory->get('system.site');

    $this->ost_config = $config_factory->get('opensearchtab.settings');

  }

  public static function create(ContainerInterface $container) {

    return new static(

      $container->get('config.factory')

    );

  }

  /**

   * {@inheritdoc}

   */

  public function content() {

    // Prepare variables for the XML content.

    $config = \Drupal::config('system.site');

    $ost_config = \Drupal::config('opensearchtab.settings');

    $short_name = !empty($ost_config->get('shortname')) ?

      $ost_config->get('shortname') : (!empty($config->get('name')) ?

        $config->get('name') : 'Drupal site');

    $description = !empty($ost_config->get('description')) ?

      $ost_config->get('description') : (!empty($config->get('slogan')) ?

        $config->get('slogan') : 'Search the site');

    $search_form_path = !empty($ost_config->get('search-form-path')) ?

    $short_name = !empty($this->ost_config->get('shortname')) ?

      $this->ost_config->get('shortname') :

      (!empty($this->system_config->get('name')) ?

        $this->system_config->get('name') : 'Drupal site');

    $description = !empty($this->ost_config->get('description')) ?

      $this->ost_config->get('description') :

      (!empty($this->system_config->get('slogan')) ?

        $this->system_config->get('slogan') : 'Search the site');

    $search_form_path = !empty($this->ost_config->get('search-form-path')) ?

      \Drupal::request()->getSchemeAndHttpHost() .

      $ost_config->get('search-form-path') :

      $this->ost_config->get('search-form-path') :

      \Drupal::request()->getSchemeAndHttpHost() . '/search/node';

    $search_path = !empty($ost_config->get('search-path')) ?

    $search_path = !empty($this->ost_config->get('search-path')) ?

      \Drupal::request()->getSchemeAndHttpHost() .

      $ost_config->get('search-path') :

      $this->ost_config->get('search-path') :

      \Drupal::request()->getSchemeAndHttpHost() .

      '/search/node?keys={searchTerms}';

    $suggestions_path_json = !empty($ost_config->get('suggestions-path-json')) ?

    $suggestions_path_json = !empty($this->ost_config->get('suggestions-path-json')) ?

      \Drupal::request()->getSchemeAndHttpHost() .

      $ost_config->get('suggestions-path-json') : '';

    $suggestions_path_xml = !empty($ost_config->get('suggestions-path-xml')) ?

      $this->ost_config->get('suggestions-path-json') : '';

    $suggestions_path_xml = !empty($this->ost_config->get('suggestions-path-xml')) ?

      \Drupal::request()->getSchemeAndHttpHost() .

      $ost_config->get('suggestions-path-xml') : '';

    $favicon_path = !empty($ost_config->get('favicon-path')) ?

      $this->ost_config->get('suggestions-path-xml') : '';

    $favicon_path = !empty($this->ost_config->get('favicon-path')) ?

      \Drupal::request()->getSchemeAndHttpHost() .

      $ost_config->get('favicon-path') : '';

      $this->ost_config->get('favicon-path') : '';

    // Define the XML content.

    $openTag = new \SimpleXMLElement(