docs: public Duration subtractTimestamp(Timestamp timestamp) {
      long durationSeconds = getSeconds() - timestamp.getSeconds();
      int durationNanos = getNanos() - timestamp.getNanos();
      if (durationSeconds < 0 && durationNanos > 0) {
        durationSeconds += 1;
        durationNanos = (int) (durationNanos - NANOS_PER_SECOND);
      } else if (durationSeconds > 0 && durationNanos < 0) {
        durationSeconds -= 1;
        durationNanos = (int) (durationNanos + NANOS_PER_SECOND);
      }
      return Duration.create(durationSeconds, durationNanos);
    }