@Override
  public void initCalendar() {
    /* code copied over from UDFWeekOfYear implementation */
    calendar.setFirstDayOfWeek(Calendar.MONDAY);
    calendar.setMinimalDaysInFirstWeek(4);
  }
Expression to get week of year.
Extends {@link VectorUDFTimestampFieldDate}
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/VectorUDFWeekOfYearDate.java