public function expand(array $options = [])
    {
        if (!empty($this->href)) {
            return $this->href;
        } else if (!empty($this->{'href-template'})) {
            $parser = new UriTemplate();
            return $parser->expand($this->{'href-template'}, $this->_convertOptions($options));
        } else {
            throw new LinkException('Cannot expand link because no href or href-template defined');
        }
    }