public function size()
    {
        $size = 0;
        if ( ! is_null($this->time)) {
            $size += 1 + Protobuf::size_varint($this->time);
        }
        if ( ! is_null($this->contents)) {
            foreach ($this->contents as $v) {
                $l = $v->size();
                $size += 1 + Protobuf::size_varint($l) + $l;
            }
        }

        return $size;
    }