Hi Stephan,
Please refer to the code example below in which we have shown how to set addInfo(custom property) to an node.
Code example:
//define addInfo property
Dictionary<string, object> addinfo = new Dictionary<string, object>();
addinfo.Add("ssgdata", "datenssg");
Palette.Items.Add(new FlowShape() { Name = "Frage", Height = 40, Width = 44, Shape = FlowShapes.Process, AddInfo = addinfo });
Regards,
Shyam G