code: public void printTo(Appendable appendable, ReadableInstant instant) throws IOException {
          long millis = DateTimeUtils.getInstantMillis(instant);
          Chronology chrono = DateTimeUtils.getInstantChronology(instant);
          printTo(appendable, millis, chrono);
      }
docs: Prints a ReadableInstant, using the chronology supplied by the instant.
  
  @param appendable  the destination to format to, not null
  @param instant  instant to format, null means now
  @since 2.0