how to use PageEvent in tapestry4 to sendRedirect to another page

public void pageValidate(P开发者_运维问答ageEvent event) {
        //how to use pageEvent to sendRedirect to google.com ?

For an external site, use:

throw new RedirectException("http://google.com")

To redirect to a page withing the application use:

throw new PageRedirectException("page");