How to clear the whole backstack for all nested NavGraphs? - android-jetpack-compose

Question

I have an application with a NavigationBar that includes three destinations. It is configured so that two of the destinations point to a seperate nested NavGraph, namely IssuesGraph and InstructionsGraph. While navigating within the nested graphs and then switching between the two destinations, the respective stack for each nested graph is saved as I wish.
NavigationBar {
val navBackStackEntry by navController.currentBackStackEntryAsState()
val currentDestination = navBackStackEntry?.destination
bottomNavigationItems.forEachIndexed { index, item ->
NavigationBarItem(
icon = { Icon(item.imageResource, stringResource(id = item.titleResource)) },
label = { Text(stringResource(id = item.titleResource)) },
selected = currentDestination?.hierarchy?.any { it.route == item.route } == true,
onClick = {
navController.navigate(item.route) {
popUpTo(navController.graph.findStartDestination().id) {
saveState = true
}
launchSingleTop = true
// Restore state when reselecting a previously selected item
restoreState = true
}
}
)
}
}
However, I now need to reset the complete navigation graph, so I want the App to display the first destination within the IssuesGraph, and if I navigate to the InstructionsGraph, it should show its first destination, too.
My NavHost looks like this:
NavHost(
modifier = modifier,
navController = navController,
startDestination = startDestination,
) {
issueGraph(navController, issuesVM)
instructionsGraph(navController, instructionsVM)
composable(Screen.SettingsScreen.route) {
SettingsScreen(
onSave = {
// Here, I want to trigger a reset of
// the backstacks of issuesGraph and instructionsGraph
// and navigate to the first screen of the issuesGraph
navController.navigate(Screen.IssuesGraph.route) {
popUpTo(navController.graph.findStartDestination().id) {
saveState = false
}
}
}
)
}
}
The seperate NavGraphs are built using the NavGraphBuilder extension function:
fun NavGraphBuilder.issueGraph(navController: NavController, issuesVM: IssuesVM) {
navigation(startDestination = Screen.IssuesHome.route, Screen.IssuesGraph.route) {
composable(Screen.IssuesHome.route) {
//...
}
}
}
The problem is, that calls like this
navController.navigate(Screen.IssuesGraph.route) {
popUpTo(navController.graph.findStartDestination().id) {
saveState = false
}
}
only clear the back stack for the nested NavGraph the the goal route Screen.IssuesGraph.route resides in. So in my case, the IssuesGraph is reset, but the InstructionsGraph isn't. When I navigate there, it still shows its previous backstack.
I already stumbled across the setGraph documentation, but couldn't understand how I could use it in my case.
Thanks for any efforts!