How can I get the "the webkit rev" and the "Chrome rev" value for webview in kotlin

I am trying to add an user agent for my webview. But I don't know how to get programmatically the value of {WebKit Rev} and {Chrome Rev}.

webview.settings.userAgentString = "Mozilla/5.0 (Linux; Android $systemVersion; $model)\n" +
                    "AppleWebKit/{WebKit Rev} (KHTML, like Gecko)\n" +
                    "Chrome/{Chrome Rev} <deviceCompat>\n" +
                    "Safari/{WebKit Rev}"