A base-64 encoded string that represents the serialized object state of the stateGraph parameter.
Any object graph that is serialized with the erload:System.Web.UI.ObjectStateFormatter.Serialize method can be deserialized with the erload:System.Web.UI.ObjectStateFormatter.Deserialize method. The ObjectStateFormatter.Serialize(object) method is used to serialize an object state graph to a base64-encoded string form.