IssueTracker

If you need to add a custom Navigator but don't want to subclass NavHost (which we expect will be needed in most cases), the correct approach is to add it before you set your graph:
1) Don't use app:navGraph in your XML
2) Get a reference to your NavController
3) Add your Navigator to the NavController
4) Call setGraph on the NavController

This relies on the fact that NavController waits until the graph is set before restoring state / doing anything at all.

Technically, the createFragmentNavigator() call in NavHostFragment is already called at the same time as your proposed onNavControllerCreated() method so as a workaround, you could override that method, add your Navigator, then return super.createFragmentNavigator().

The first solution does not work, because after screen rotation, the graph (probably a restored graph) is set when Activity.setContentView() is called.

The workaround with createFragmentNavigator() works, though it's not very elegant. Maybe the method could be renamed to createNavigators() and return a list or an array of Navigators?
Anyway, it is a good enough solution for now, so it is not very urgent.

In conclusion:
* I think that a better support for custom destinations should be provided before final release.
* I would suggest describing the "Add support for new destination types" section in the documentation in more details.

Thank you

I suspect the issue you're running into for the first solution is that you're using the setGraph(R.navigation.graph) method, which does indeed cause it to automatically inflate the graph by id on rotation. Using setGraph(navGraph) where navGraph is a navGraph object you've inflated with navController.getNavInflater().inflate(R.navigation.graph) will never automatically be recreated.

Definitely something we can do better on though :)