public static void getInvite(@Required @Email String email, String returnUrl) throws Throwable {
   if (validation.hasErrors()) {
     flash.error(Messages.get("web.invite.email.invalid"));
     params.flash();
   } else {
     if (User.findByEmail(email) != null) {
       flash.error(Messages.get("web.invite.email.exists"));
       params.flash();
     } else {
       // Create the invitation instance.
       String lang = Lang.get();
       Invitation invite = new Invitation();
       invite.email = email;
       invite.locale = lang;
       invite.insert();
       flash.success(Messages.get("web.invite.success"));
     }
   }
   if (StringUtils.isBlank(returnUrl)) {
     Application.index();
   }
   redirect(returnUrl);
 }