1) Exact steps to reproduce the problem
Create a Calendar with locale=si (Slovenia) and print getFirstDayOfWeek(). It returns Sunday instead of Monday.

2) Source Code that demonstrates the problem
      System.out.println ("First day of week for sl locale is " +
Calendar.getInstance (new Locale ("sl")).getFirstDayOfWeek());
      System.out.println ("First day of week for sl_SI locale is " +
Calendar.getInstance (new Locale ("sl", "SI")).getFirstDayOfWeek());
      System.out.println ("Calendar.SUNDAY = " + Calendar.SUNDAY + ", Mon = " + Calendar.MONDAY);

Output:
First day of week for sl locale is 1
First day of week for sl_SI locale is 1
Calendar.SUNDAY = 1, Mon = 2