Belongs to medium article

MainActivity.kt

class MainActivity : FlutterActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        GeneratedPluginRegistrant.registerWith(this)

        MethodChannel(flutterView, "android_app_retain").apply {
            setMethodCallHandler { method, result ->
                if (method.method == "sendToBackground") {
                    moveTaskToBack(true)
                }
            }
        }
    }
}