WCF post json and return json

[OperationContract] 
        [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.WrappedRequest)] 
        [SwaggerWcfTag(nameof(GetUTCRange))] 
        [SwaggerWcfContentTypes(new 					string[] { "text/plain" })] 
 			public Stream GetUTCRange(Stream streamdata) 
        { 
 			using (StreamReader reader = new StreamReader(stream)) 
            { 
 			string res = reader.ReadToEnd(); 
                reader.Close(); 
                // return res; //读取动态JSON参数 
            } 
            WebOperationContext.Current.OutgoingResponse.ContentType = "application/json";  //修改返回的声明  
 			return 					new JsonResponse() { code = 1, msg = $"invalid tableName {json.tableName}" }.ToStream(); 
        } 
 			public 					static Stream ToStream(this JsonResponse json, bool none = true) 
        { 
 			return 					new MemoryStream(System.Text.Encoding.UTF8.GetBytes(json.Serialize(none))); 
        }