public function createSubProfileQuery()
    {
        if (!$this->isFirstSample || !self::$profilerIsEnabled) {
            return null;
        }

        $features = $this->args;

        if (isset($features['sub_profile']) && false !== strpos($features['sub_profile'], ':')) {
            $subProfile = explode(':', $features['sub_profile'], 2);
            $subProfile = $subProfile[1];
        } else {
            $subProfile = '';
        }
        $features['sub_profile'] = $subProfile.':'.$this->generateSubId();

        unset($features['aggreg_samples']);

        return $this->challenge.'&'.'signature='.$this->signature.'&'.strtr(http_build_query($features, '', '&'), self::$urlEncMap);
    }