onCloseWindow property Null safety

(void Function?(InAppWebViewController controller)?) onCloseWindow
final

Event fired when the host application should close the given WebView and remove it from the view system if necessary. At this point, WebCore has stopped any loading in this window and has removed any cross-scripting ability in javascript.

Official Android API: https://developer.android.com/reference/android/webkit/WebChromeClient#onCloseWindow(android.webkit.WebView)

Official iOS API: https://developer.apple.com/documentation/webkit/wkuidelegate/1537390-webviewdidclose

Implementation

final void Function(InAppWebViewController controller)? onCloseWindow;