code: protected function renderSortLinks()
      {
          $attributes = empty($this->attributes) ? array_keys($this->sort->attributes) : $this->attributes;
          $links = [];
          foreach ($attributes as $name) {
              $links[] = $this->sort->link($name, $this->linkOptions);
          }
  
          return Html::ul($links, array_merge($this->options, ['encode' => false]));
      }
docs: Renders the sort links.
  @return string the rendering result