return periodEnd.minusDays(lessonEndDayOfWeek - getLessonWeekDay());
return periodEnd.minusDays(lessonEndDayOfWeek - getLessonWeekDayToYearMonthDayFormat());
    private YearMonthDay getLessonEndDay() {        YearMonthDay periodEnd = getRoomOccupation().getPeriod().getEndYearMonthDay();           int lessonEndDayOfWeek = periodEnd.toDateTimeAtMidnight().getDayOfWeek();        return periodEnd.minusDays(lessonEndDayOfWeek - getLessonWeekDay());    }