code: function (field) {
              if (MIN_VALUES[field] !== undefined) {
                  return MIN_VALUES[field];
              }
              var fields = this.fields;
              if (field === WEEK_OF_MONTH) {
                  var cal = new GregorianCalendar(fields[YEAR], fields[MONTH], 1);
                  return cal.get(WEEK_OF_MONTH);
              }
              throw new Error('minimum value not defined!');
          }
docs: Returns the minimum value for
  the given calendar field of this GregorianCalendar instance.
  The minimum value is defined as the smallest value
  returned by the get method for any possible time value,
  taking into consideration the current values of the getFirstDayOfWeek,
  getMinimalDaysInFirstWeek.
  @param field the calendar field.
  @returns {Number} the minimum value for the given calendar field.