private function getHighlight()
    {
        if (Utils::findKey($this->options, 'highlight', false))
        {
            foreach ($this->fields as $field)
            {
                $this->payload['highlight']['fields'][$field] = new StdClass();
            }

            if ($tag = Utils::findKey($this->options['highlight'], 'tag', false))
            {
                $this->payload['highlight']['pre_tags'] = [$tag];
                $this->payload['highlight']['post_tags'] = [preg_replace('/\A</', '</', $tag)];
            }
        }
    }