修复银联通过订单号无法撤销和退款的问题

src/PaySharp.Unionpay/Domain/BaseModel.cs

@@ -23,7 +23,7 @@ namespace PaySharp.Unionpay.Domain
         /// <summary>
         /// 订单发送时间
         /// </summary>
-        public string TxnTime { get; internal set; } = DateTime.Now.ToString("yyyyMMddHHmmss");
+        public string TxnTime { get; } = DateTime.Now.ToString("yyyyMMddHHmmss");
 
         /// <summary>
         /// 交易类型

src/PaySharp.Unionpay/Domain/CancelModel.cs

@@ -1,4 +1,5 @@
 using PaySharp.Core;
+using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 
@@ -44,6 +45,11 @@ namespace PaySharp.Unionpay.Domain
         /// </summary>
         public string OrigOrderId { get; set; }
 
+        /// <summary>
+        /// 原交易商户发送交易时间
+        /// </summary>
+        public string OrigTxnTime { get; } = DateTime.Now.ToString("yyyyMMddHHmmss");
+
         /// <summary>
         /// 保留域
         /// </summary>

src/PaySharp.Unionpay/Domain/RefundModel.cs

@@ -1,4 +1,5 @@
 using PaySharp.Core;
+using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 
@@ -44,6 +45,11 @@ namespace PaySharp.Unionpay.Domain
         /// </summary>
         public string OrigOrderId { get; set; }
 
+        /// <summary>
+        /// 原交易商户发送交易时间
+        /// </summary>
+        public string OrigTxnTime { get; } = DateTime.Now.ToString("yyyyMMddHHmmss");
+
         /// <summary>
         /// 控制规则
         /// </summary>