As far as I can tell there is no way for a graph implementation to specify a classresolver for the following code:
The problem is that inside the graph implementation we need to be able to do this:
but only supplying a registry is supported.
Other solutions could be to design GryoIo for extension so that it can be wrapped or to change the signature of Graph#io to:
I would probably go for the signature change, so the graph is responsible for deciding the implementation that is returned.