The DateExpression can be used to construct a static date object. The Calendar object used as base is initialized to
the current date. Fields that are not set, are ignored.
To construct dates from values read from the data-row, use the
VariableDateExpression instead.
author: Thomas Morgner
Create a new calendar instance. This implementation uses Calendar.getInstance(..) to create the Calendar,
and therefore the result depends on the locale of the report.
the calendar.