mAppUpdateManager = AppUpdateManagerFactory.create(this);

mAppUpdateManager.registerListener(installStateUpdatedListener);

mAppUpdateManager.getAppUpdateInfo().addOnSuccessListener(appUpdateInfo -> {

        if (appUpdateInfo.updateAvailability() == UpdateAvailability.UPDATE_AVAILABLE
                && appUpdateInfo.isUpdateTypeAllowed(AppUpdateType.FLEXIBLE /*AppUpdateType.IMMEDIATE*/)){

            try {    
                    mAppUpdateManager.startUpdateFlowForResult(
                            appUpdateInfo, AppUpdateType.FLEXIBLE /*AppUpdateType.IMMEDIATE*/, MainActivity.this, RC_APP_UPDATE);

            } catch (IntentSender.SendIntentException e) {
                e.printStackTrace();
            }

        } else if (appUpdateInfo.installStatus() == InstallStatus.DOWNLOADED){
            //CHECK THIS if AppUpdateType.FLEXIBLE, otherwise you can skip
            popupSnackbarForCompleteUpdate();
        } else {
            Log.e(TAG, "checkForAppUpdateAvailability: something else");
        }
    });