public void setVisibleYearCount(int numberOfYears) {
        if (numberOfYears <= 0) {
            throw new IllegalArgumentException("The number of years to display must be positive");
        }

        visibleYearCount = numberOfYears;
        getMonthSelector().refresh();
    }
Set the number of years to display in the years selection dropdown. The range of years will be
centered on the selected date.
stroom-core-client-widget/src/main/java/stroom/widget/datepicker/client/CustomDatePicker.java