public function createGeoIndex($collectionId, array $fields, $geoJson = null)
    {
        $indexOptions = [];

        if ($geoJson) {
            $indexOptions[self::OPTION_GEOJSON] = (bool) $geoJson;
        }

        return $this->index($collectionId, self::OPTION_GEO_INDEX, $fields, null, $indexOptions);
    }