fix issue #I3ODI5 swagger增加分组的功能

fix issue #I3PE3R 会签节点异常,提示'-1' was not present in ...
fix CodeSmith生成的后端代码报错 https://gitee.com/yubaolee/OpenAuth.Core/issues/I3OXJZ

OpenAuth.App/Flow/FlowRuntime.cs

@@ -449,7 +449,7 @@ namespace OpenAuth.App.Flow
         /// <summary>
         /// 下一个节点对象
         /// </summary>
-        public FlowNode nextNode => Nodes[nextNodeId];
+        public FlowNode nextNode => nextNodeId != "-1"? Nodes[nextNodeId] : null;
 
         /// <summary>
         /// 上一个节点

OpenAuth.App/Test/TestFlow.cs

@@ -63,6 +63,15 @@ namespace OpenAuth.App.Test
             
         }
 
+        [Test]
+        public void GetDetail()
+        {
+            var app = _autofacServiceProvider.GetService<FlowInstanceApp>();
+            var flowinstance = app.GetForVerification("80e9db5f-419b-4b65-a274-abe2660608dd");
+            Console.WriteLine(JsonHelper.Instance.Serialize(flowinstance));
+
+        }
+
 
         [Test]
         public void Verificate()