code: @Override  // override for Javadoc and performance
      public String format(DateTimeFormatter formatter) {
          Objects.requireNonNull(formatter, "formatter");
          return formatter.format(this);
      }
docs: Formats this date-time using the specified formatter.
  <p>
  This date-time will be passed to the formatter to produce a string.
  
  @param formatter  the formatter to use, not null
  @return the formatted date-time string, not null
  @throws DateTimeException if an error occurs during printing