class HelpSectionManager

class HelpSectionManager extends CoreHelpSectionManager {
    
    /**
     * The search manager.
     *
     * @var \Drupal\Component\Plugin\PluginManagerInterface
     */
    protected $searchManager;
    
    /**
     * Sets the search manager.
     *
     * @param \Drupal\Component\Plugin\PluginManagerInterface|null $search_manager
     *   The search manager if the Search module is installed.
     */
    public function setSearchManager(PluginManagerInterface $search_manager = NULL) {
        $this->searchManager = $search_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public function clearCachedDefinitions() {
        parent::clearCachedDefinitions();
        if ($this->searchManager && $this->searchManager
            ->hasDefinition('help_search') && $this->moduleHandler
            ->moduleExists('help_topics')) {
            // Rebuild the index on cache clear so that new help topics are indexed
            // and any changes due to help topics edits or translation changes are
            // picked up.
            $help_search = $this->searchManager
                ->createInstance('help_search');
            $help_search->markForReindex();
        }
    }

}