text: public static DVConstraint CreateDateConstraint(int comparisonOperator, String expr1, String expr2, String dateFormat){if (expr1 == null){throw new ArgumentException("expr1 must be supplied");}OperatorType.ValidateSecondArg(comparisonOperator, expr2);SimpleDateFormat df = dateFormat == null ? null : new SimpleDateFormat(dateFormat);String formula1 = GetFormulaFromTextExpression(expr1);Double value1 = formula1 == null ? ConvertDate(expr1, df) : Double.NaN;String formula2 = GetFormulaFromTextExpression(expr2);Double value2 = formula2 == null ? ConvertDate(expr2, df) : Double.NaN;return new DVConstraint(ValidationType.DATE, comparisonOperator, formula1, formula2, value1, value2, null);}