Diferents Datetime libraries in java and Vaadin?

Im having a problem with the visible days for my Calendar. I have an inner enum, and I dont know if it is about the Calendar date libraries:

CalendarDays { LV , LVS, ALLWEEK } ; (LV: Monday to Friday, LVS: Monday to Saturday and ALLWEEK is for all week)

switch(calType){
                     case LV:
                                  widgetCalendar.setFirstVisibleDayOfWeek(1);
                                   widgetCalendar.setLastVisibleDayOfWeek(5);
                                   break;
                   case LVS:
                                  widgetCalendar.setFirstVisibleDayOfWeek(1);
                                  widgetCalendar.setLastVisibleDayOfWeek(6);
                                 break;
                    case ALLWEEK:
                   default:
                                   widgetCalendar.setFirstVisibleDayOfWeek(1);
                                   widgetCalendar.setLastVisibleDayOfWeek(7);
                                  break;
}

According to java 1.8 Calendar API Monday =1, Tuesday =2, … Sunday = 7, but on the Vaadin Demo Sampler, is not like that, its like : Sunday = 1, Monday = 2 … Saturday = 7, which is the correct way?, I will think the first one, because on the Vaadin Calendar Component Api sais that the rule for the FirstVisibleDayOfWeek < LastVisibleDayOfWeek (https://vaadin.com/api/com/vaadin/ui/Calendar.html#getFirstVisibleDayOfWeek()), but Im having problems with the navigation of the calendar for the case LV, and LVS, for example in the case LVS on the Weekly View I can see Saturday and enter on the day Saturday, but on Day View I cannot navigate to Saturday, it goes from Friday to Monday.

I using java 1.8_25 and Vaadin version 7.5.2