“ Details here: https://stackoverflow.com/q/53688934/1229936 ”
“ Sample Code: https://github.com/jeffreyfhow/NestedNavFragmentsTest ”
“ https://android-review.googlesource.com/846338 adds a setFallbackOnNavigateUpListener method on AppBarConfiguration that allows you to register an OnNavigateUpListener to handle cases where navController.navigateUp() return false. ”