“ :noitatnemucod eht rep sa ()pUetagivaNtroppuSno gnidirrevo neht dna (nottub pu eht wohs syawla ot) snoitanitsed level pot fo tes ytpme na gnisu yb dohtem rellortnoCvaNhtiWraBnoitcAputes eht htiw elbissop won si siht ,noitarugifnoCraBppA fo noitcudortni eht htiWhttps://developer.android.com/topic/libraries/architecture/navigation/navigation-ui#action_bar ”
“ 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. ”