fixed concurrency issue

Author: vadzim-vys

instrumentation-tests/src/androidTest/java/com/mapbox/navigation/instrumentation_tests/core/PreviewRoutesTest.kt

@@ -46,7 +46,7 @@ class PreviewRoutesTest : BaseTest<EmptyTestActivity>(EmptyTestActivity::class.j
     @Test
     fun preview_routes() = sdkTest(timeout = Long.MAX_VALUE) {
         val routes = RoutesProvider.dc_short_with_alternative(activity).toNavigationRoutes()
-        //mapboxNavigation.startTripSession() <- this breaks tests because of resetting the route
+        mapboxNavigation.startTripSession()
         val previewedRouteDeffer = async {
             mapboxNavigation.waitForPreviewRoute()
         }

libnavigation-core/src/main/java/com/mapbox/navigation/core/MapboxNavigation.kt

@@ -838,16 +838,20 @@ class MapboxNavigation @VisibleForTesting internal constructor(
         routes: List<NavigationRoute>,
         initialLegIndex: Int = 0,
     ) {
-        val alternatives = routes.drop(1)
-        val routesData = RouteParser.createRoutesData(
-            routes.first().nativeRoute(),
-            alternatives.map { it.nativeRoute() }
-        )
-        routeAlternativesController.processAlternativesMetadata(
-            routes,
-            routesData.alternativeRoutes()
-        )
-        directionsSession.setRoutes(routes, BasicSetRoutesInfo(RoutesExtra.ROUTES_UPDATE_REASON_PREVIEW, initialLegIndex))
+        threadController.getMainScopeAndRootJob().scope.launch(Dispatchers.Main.immediate) {
+            routeUpdateMutex.withLock {
+                val alternatives = routes.drop(1)
+                val routesData = RouteParser.createRoutesData(
+                    routes.first().nativeRoute(),
+                    alternatives.map { it.nativeRoute() }
+                )
+                routeAlternativesController.processAlternativesMetadata(
+                    routes,
+                    routesData.alternativeRoutes()
+                )
+                directionsSession.setRoutes(routes, BasicSetRoutesInfo(RoutesExtra.ROUTES_UPDATE_REASON_PREVIEW, initialLegIndex))
+            }
+        }
     }
 
     fun setPreviewedRoute() {