code: public YearWeek minusYears(long yearsToSubtract) {
          if (yearsToSubtract == 0) {
              return this;
          }
          int newYear = Math.toIntExact(Math.subtractExact(year, yearsToSubtract));
          return withYear(newYear);
      }
docs: Returns a copy of this year-week with the specified number of years subtracted.
  <p>
  If the week of this instance is 53 and the new year does not have 53 weeks,
  the week will be adjusted to be 52.
  <p>
  This instance is immutable and unaffected by this method call.
  
  @param yearsToSubtract  the years to subtract, may be negative
  @return the year-week with the years subtracted, not null