code: public void printTo(StringBuffer buf, long instant) {
          try {
              printTo((Appendable) buf, instant);
          } catch (IOException ex) {
              // StringBuffer does not throw IOException
          }
      }
docs: Prints an instant from milliseconds since 1970-01-01T00:00:00Z,
  using ISO chronology in the default DateTimeZone.
  
  @param buf  the destination to format to, not null
  @param instant  millis since 1970-01-01T00:00:00Z