onReceivedClientCertRequest property Null safety
Notify the host application to handle an SSL client certificate request. Webview stores the response in memory (for the life of the application) if ClientCertResponseAction.PROCEED or ClientCertResponseAction.CANCEL is called and does not call onReceivedClientCertRequest again for the same host and port pair. Note that, multiple layers in chromium network stack might be caching the responses.
challenge contains data about host, port, protocol, realm, etc. as specified in the ClientCertChallenge.
final Future<ClientCertResponse?> Function( InAppWebViewController controller, ClientCertChallenge challenge)? onReceivedClientCertRequest;