protected function findPlaceholderStartPos($path) {
        $brFgPos = strpos($path, '{');
        $brSqPos = strpos($path, '[');
        if ($brFgPos === false && $brSqPos === false) {
            return false;
        }
        $len = strlen($path);
        $positions = [
            $brFgPos !== false ? $brFgPos : $len,
            $brSqPos !== false ? $brSqPos : $len,
        ];
        return min($positions);
    }