For development purposes, it would be nice to have prettified (property intented) JSON strings.
So maybe update the api to be
class JsonSaveContainer: BaseSerializationSaveContainer
{
proto string ExportToString(bool pretty = false);
proto external bool SaveToFile(string fileName, bool pretty = false);
...
}or
class JsonSaveContainer: BaseSerializationSaveContainer
{
...
proto external void SetPrettyPrint(bool pretty = false);
}