code: public function getTag()
      {
          if (null !== $this->tag) {
              return $this->tag;
          }
  
          $categoryId = $this->getEvent()->getRouteMatch()->getParam('categoryid');
          if (is_numeric($categoryId)) {
              return $this->tag = $this->getDiscussService()->getCategoryById($categoryId);
          }
  
          // Find category by topic
          $topicId = $this->getEvent()->getRouteMatch()->getParam('topicid');
          if (is_numeric($topicId)) {
              // Fetch the topic
              $topic = $this->getDiscussService()->getTopicById($topicId);
  
              // Fetch the category
              return $this->tag = $this->getDiscussService()->getCategoryById($topic->getforumCategoryId());
          }
  
          return false;
      }
docs: Retrieve the category by the set url
  
  @access public
  @author Stijn
  @version 1.0.0
  @return boolean / CategoryInterface