code: protected function initTemplateAssetsManager()
      {
          $templateAssetsManager = $this->options["template_assets"];
          $pluginManager = $this->options["plugin_manager"];
          $templateAssetsManager
              ->backend()
              ->add($pluginManager->getAssets())
          ;
  
          return $templateAssetsManager;
      }
docs: Initializes the template assets manager object
  
  @return TemplateAssetsManager