code: public CalendarWeek plus(Years<Weekcycle> years) {
  
          if (years.isEmpty()) {
              return this;
          }
  
          int y = MathUtils.safeAdd(this.year, years.getAmount());
          int effectiveWeek = this.week;
  
          if ((this.week == 53) && (maximumOfWeek(y) < 53)) {
              effectiveWeek = 52;
          }
  
          return CalendarWeek.of(y, effectiveWeek);
  
      }
docs: /*[deutsch]
  <p>Addiert die angegebenen Jahre zu dieser Kalenderwoche. </p>
  
  @param   years       the count of week-based years to be added
  @return  result of addition