Can you convert the following code from C# version 10.0 to 7.3

   // Classes
        public class CPTransaction
        {
            [Name("ClientID")]
            public int ClientID { get; set; }

            [Name("TransactionDate")]
            public DateTime TransactionDate { get; set; }

            [Name("PostDate")]
            public DateTime PostDate { get; set; }

            [Name("Description")]
            public string? Description { get; set; }

            [Name("Category")]
            public string? Category { get; set; }

            [Name("Amount")]
            public double Amount { get; set; }

            [Name("RunningBalance")]
            public double RunningBalance { get; set; }

            [Name("EODBalance")]
            public double EODBalance { get; set; }

            [Name("DayOfWeek")]
            public string? DayOfWeek { get; set; }

            public override string ToString()
            {
                return $"Transaction on {TransactionDate.ToShortDateString()}: {Description} ({Amount:C})";
            }

        }

        public class MNTransaction
        {
            [Name("ClientID")]
            public int ClientID { get; set; }

            [Name("TransactionDate")]
            public DateTime TransactionDate { get; set; }

            public override string ToString()
            {
                return $"Transaction on {TransactionDate.ToShortDateString()}";
            }
        }

        public class NewBalanceTransaction
        {
            [N Wrap the entire output in JSON format.
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