code: @Override  // override with covariant return type
      public LocalDate date(int prolepticYear, int month, int dayOfMonth) {
          return LocalDate.of(prolepticYear, month, dayOfMonth);
      }
docs: Obtains an ISO local date from the proleptic-year, month-of-year
  and day-of-month fields.
  <p>
  This is equivalent to {@link LocalDate#of(int, int, int)}.
  
  @param prolepticYear  the ISO proleptic-year
  @param month  the ISO month-of-year
  @param dayOfMonth  the ISO day-of-month
  @return the ISO local date, not null
  @throws DateTimeException if unable to create the date