Refactor and remove isStartDestinationSameWithNextDestination

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/NiaAppState.kt

@@ -143,10 +143,10 @@ class NiaAppState(
         trace("Navigation: ${topLevelDestination.name}") {
             val topLevelNavOptions = navOptions {
                 val startDestination = navController.graph.findStartDestination()
+
                 // Avoid popUpTo and navigate to same screen.
-                val shouldNotSavedAndRestored = isStartDestinationSameWithNextDestination(
-                    startDestination, topLevelDestination
-                ) ?: false
+                val shouldNotSavedAndRestored = startDestination.hasRoute(topLevelDestination.route)
+
                 // Pop up to the start destination of the graph to
                 // avoid building up a large stack of destinations
                 // on the back stack as users select items
@@ -168,14 +168,6 @@ class NiaAppState(
         }
     }
 
-    /**
-     * Check if next destination is same with start destination of current graph.
-     */
-    private fun isStartDestinationSameWithNextDestination(
-        startDestination: NavDestination,
-        nextDestination: TopLevelDestination,
-    ): Boolean? = startDestination.hasRoute(nextDestination.route)
-
     fun navigateToSearch() = navController.navigateToSearch()
 }