/**
  * Hooks into the wp_async_set_sermon_terms action, which is triggered when a post is saved.
  *
  * @since 0.1.1
  *
  * @param int    $post_id  Post ID
  * @param string $taxonomy Taxonomy
  */
 public function trigger_cache_flush($post_id, $taxonomy)
 {
     if ($this->taxonomy() !== $taxonomy || $this->sermons->post_type() !== get_post_type($post_id)) {
         return;
     }
     $this->get_terms_in_sermon_date_order(1);
 }