Firebase server timestamp

firebaseservertimestamp.cs

    class ServerValue {
        [JsonProperty(".sv")]
        public string Value {get; set;}
    }
    
    class TimestampedObject
    {
        public TimestampedObject()
        {
            this.Timestamp = new ServerValue {
                Value = "timestamp"
            };
        }
        public ServerValue Timestamp { get; set; } 
    }