code: @Override  // override with covariant return type
      public LocalDate dateYearDay(Era era, int yearOfEra, int dayOfYear) {
          return dateYearDay(prolepticYear(era, yearOfEra), dayOfYear);
      }
docs: Obtains an ISO local date from the era, year-of-era and day-of-year fields.
  
  @param era  the ISO era, not null
  @param yearOfEra  the ISO year-of-era
  @param dayOfYear  the ISO day-of-year
  @return the ISO local date, not null
  @throws DateTimeException if unable to create the date