Does the audioprocessorgraph getstateinformation really not do anything?
I am looking at the code and it is simply an empty function. 
What would you expect it to do?
Rail
It’s where you save to disk, although a bit confusingly to me it’s called “get…”, your plugin parameters.
Likewise “setStateInformation” is loading your plugin parameters.
In both it is up to you to put in code as to what you are saving and retrieving.
Just after my quick glance of the documentation it looked like it wasn’t virtual so I assumed it would be implemented in some capacity. but yeah basically default saving connection and node state or something would be nice but it ain’t no thang I’m working on it now. I realize it may be rather inflexible to have it implemented but I can dreamm