Method setWeek

base/src/main/java/net/time4j/Weekmodel.java:1948–1962

(
            PlainDate date,
            int value
        )

        }

        private PlainDate setWeek(
            PlainDate date,
            int value
        ) {

            int old = this.getWeek(date);

            if (value == old) {
                return date;
            } else {
                int delta = 7 * (value - old);
                return date.withDaysSinceUTC(date.getDaysSinceUTC() + delta);
            }

        }

        // Länge eines Jahres/Monats in Tagen
        private int getLengthOfYM(PlainDate date) {