code: @Override
      public JapaneseDate dateYearDay(int prolepticYear, int dayOfYear) {
          LocalDate date = LocalDate.ofYearDay(prolepticYear, dayOfYear);
          return date(prolepticYear, date.getMonthValue(), date.getDayOfMonth());
      }
docs: Obtains a local date in Japanese calendar system from the
  proleptic-year and day-of-year fields.
  <p>
  The day-of-year in this factory is expressed relative to the start of the proleptic year.
  The Japanese proleptic year and day-of-year are the same as those in the ISO calendar system.
  They are not reset when the era changes.
  
  @param prolepticYear  the proleptic-year
  @param dayOfYear  the day-of-year
  @return the Japanese local date, not null
  @throws DateTimeException if unable to create the date