I think that refers to this PR (https://github.com/appium/appium-uiautomator2-server/pull/11117)
You can explore it by using the tests they implemented, such as https://github.com/vmaxim/appium-uiautomator2-server/blob/master/app/src/test/java/io/appium/uiautomator2/model/NotificationListenerTests.java11
The settings enableNotificationListener is in documentation in here: http://appium.io/docs/en/advanced-concepts/settings/#supported-settings11
There was a very informative webinar on this release from Jonathan himself.
Do wattch with your team
https://info.perfectomobile.com/appium_w_jonathanlipps_odw.html39
You have dmg for appium-desktop (https://github.com/appium/appium-desktop/releases29).
To automate iOS11.3 I think you should have appium 1.8 and XCode9.3
@pushpank I am facing the Same Issue(Returned value cannot be converted to WebElement) and when I tried to Down grade it to 1.6.1 It is Showing 1.6.1 in the when i tap “About Appium” from menu on the mac.When i check for Updates its saying “up to date”.Let me know if you could be able to resolve some how Thanks.