missing GMT offset in LogMessageTime

[yaojingguo]

I am trying to use Custom Log Prefix Format to format log time as ISO8601 format. So I need time GMT offset. But LogMessageTime does not expose time_struct's tm_gmtoff field.

struct LogMessageTime {
  explicit LogMessageTime (const struct::tm& time_struct_,
                           const time_t& timestamp_, const int32_t& usecs_):
      time_struct(time_struct_), ts(timestamp_), usecs(usecs_) {}

  const time_t& timestamp() const { return ts; }
  const int& sec() const { return time_struct.tm_sec; }
  const int32_t& usec() const { return usecs; }
  const int& min() const { return time_struct.tm_min; }
  const int& hour() const { return time_struct.tm_hour; }
  const int& day() const { return time_struct.tm_mday; }
  const int& month() const { return time_struct.tm_mon; }
  const int& year() const { return time_struct.tm_year; }
  const int& dayOfWeek() const { return time_struct.tm_wday; }
  const int& dayInYear() const { return time_struct.tm_yday; }
  const int& dst() const { return time_struct.tm_isdst; }

  private:
    const struct::tm& time_struct;
    const time_t& ts;
    const int32_t& usecs;
};

Is it possible to add the following code to LogMessageTime?

const int& gmtoff() const { return time_struct.gmtoff; }