code: public Moment at(ZonalOffset offset) {
  
          long localSeconds =
              MathUtils.safeMultiply(
                  this.date.getDaysSinceUTC() + 2 * 365,
                  86400);
          localSeconds += (this.time.getHour() * 3600);
          localSeconds += (this.time.getMinute() * 60);
          localSeconds += this.time.getSecond();
  
          int localNanos = this.time.getNanosecond();
          long posixTime = localSeconds - offset.getIntegralAmount();
          int posixNanos = localNanos - offset.getFractionalAmount();
  
          if (posixNanos < 0) {
              posixNanos += MRD;
              posixTime--;
          } else if (posixNanos >= MRD) {
              posixNanos -= MRD;
              posixTime++;
          }
  
          return Moment.of(posixTime, posixNanos, TimeScale.POSIX);
  
      }
docs: /*[deutsch]
  <p>Kombiniert diesen lokalen Zeitstempel mit dem angegebenen
  Zeitzonen-Offset zu einem globalen UTC-Moment. </p>
  
  @param   offset  timezone offset
  @return  global UTC-moment based on this local timestamp interpreted
  at given offset
  @since   1.2
  @see     #atUTC()
  @see     #in(Timezone)