How to convert Vaddin 8 BrowserFrame for Vaadin 23?

I used BrowserFrame in my Vaadin 8 application to run a different application in the bottomlayout :

BrowserFrame m_browser = new BrowserFrame();
m_browser.setSource(new ExternalResource(aMyAppURL + “/add?user=”
+URLEncoder.encode(“testuser”, “UTF-8”)
+URLEncoder.encode("testpassword, “UTF-8”)));

As above, I passed the application user and password as parameters.
What will be the best solution to convert this code to Vaddin 23?

Thank you,