In Merlin beta, the calendar system for the Thai locale is implemented as a GregorianCalendar subclass, sun.util.BuddhistCalendar. However, BuddhistCalendar doesn't maintain the semantic of Gregorian years and it's very likely to break existing applications which rely on such Gregorian calendar semantic. In addition, since BuddhistCalendar is a Sun private class, applications can't distinguish it from a real GregorianCalendar instance.