code: public function isEmpty()
      {
          @trigger_error(__METHOD__.' is deprecated and will be removed in 3.0.', E_USER_DEPRECATED);
  
          return null === $this->id && ('' === $this->content || null === $this->content);
      }
docs: Check if token is empty, e.g. because of clearing.
  
  @return bool
  
  @deprecated since 2.4