successfully submitted. This callback will be passed two arguments. A JS Object containing the values that were submitted and a String url of the follow up page that the user will be forwarded to, or null or empty string if there is no configured follow up page.Special behavior: If this callback returns a false (measured using ===) then the visitor will NOT be forwarded to the follow up page and the page will NOT be reloaded. This allows the implementor to do extra processing to the follow up url, or to take actio