I'm trying to create a Node System using GraphView

Shadergraph seems to have some sort of way to attach a default value to a node, as seen in this image: 171896-captura-de-pantalla-2020-12-01-174741.png

However, there doesn’t seem to be any variable inside the Port or Node class that resembles any sort of “default value”.
Can anyone help me out?

Think of the “default value” as its own node. Imagine you instantiate a node that should have a default value, you would just instantiate a “Value” node (with your desired default value) that is connected to the port which you want to have a default value together with your main node.