code: public static JulianDate of(int prolepticYear, int month, int dayOfMonth) {
          return JulianDate.create(prolepticYear, month, dayOfMonth);
      }
docs: Obtains a {@code JulianDate} representing a date in the Julian calendar
  system from the proleptic-year, month-of-year and day-of-month fields.
  <p>
  This returns a {@code JulianDate} with the specified fields.
  The day must be valid for the year and month, otherwise an exception will be thrown.
  
  @param prolepticYear  the Julian proleptic-year
  @param month  the Julian month-of-year, from 1 to 12
  @param dayOfMonth  the Julian day-of-month, from 1 to 31
  @return the date in Julian calendar system, not null
  @throws DateTimeException if the value of any field is out of range,
  or if the day-of-month is invalid for the month-year