code: public Instant toInstant(ZoneOffset offset) {
          return Instant.ofEpochSecond(toEpochSecond(offset), toLocalTime().getNano());
      }
docs: Converts this date-time to an {@code Instant}.
  <p>
  This combines this local date-time and the specified offset to form
  an {@code Instant}.
  
  @param offset  the offset to use for the conversion, not null
  @return an {@code Instant} representing the same instant, not null