Fix the bug for flow is empty

v2rayN/v2rayN/Handler/CoreConfigSingbox.cs

@@ -255,7 +255,6 @@ namespace v2rayN.Handler
                     outbound.type = Global.vlessProtocolLite;
 
                     outbound.uuid = node.id;
-                    outbound.flow = node.flow;
 
                     outbound.packet_encoding = "xudp";
 
@@ -263,6 +262,10 @@ namespace v2rayN.Handler
                     {
                         outboundMux(node, outbound);
                     }
+                    else
+                    {
+                        outbound.flow = node.flow;
+                    }
                 }
                 else if (node.configType == EConfigType.Trojan)
                 {

v2rayN/v2rayN/Handler/CoreConfigV2ray.cs

@@ -423,7 +423,6 @@ namespace v2rayN.Handler
                         usersItem = vnextItem.users[0];
                     }
                     usersItem.id = node.id;
-                    usersItem.flow = string.Empty;
                     usersItem.email = Global.userEMail;
                     usersItem.encryption = node.security;
 
@@ -462,7 +461,6 @@ namespace v2rayN.Handler
                     serversItem.address = node.address;
                     serversItem.port = node.port;
                     serversItem.password = node.id;
-                    serversItem.flow = string.Empty;
 
                     serversItem.ota = false;
                     serversItem.level = 1;

v2rayN/v2rayN/Mode/V2rayConfig.cs

@@ -185,7 +185,7 @@ namespace v2rayN.Mode
         /// <summary>
         /// VLESS
         /// </summary>
-        public string flow { get; set; }
+        public string? flow { get; set; }
     }
 
     public class Sniffing4Ray