1. @override
void onCreated()

Callback used to notify a node that it was created. This is called after a node is deserialized as well.

Source 

@override
void onCreated() {
  if (configs.containsKey(r"$version")) {
    var version = configs[r"$version"];
    if (version != latestVersion) {
      upgrader(version);
      configs[r"$version"] = latestVersion;
    }
  } else {
    configs[r"$version"] = latestVersion;
  }
}