WebDriverBackedSelenium：确认处理抛出：UnsupportedOperationException

Question

我在测试中使用 WebDriverBackedSelenium 处理确认对话框和警报

    WebDriver driver = new FirefoxDriver();
    driver.get("https://uat03.testnet.com/uat03/main.asp");

    Selenium selenium = new WebDriverBackedSelenium(driver,"https://uat03.testnet.com/uat03/main.asp");

    WebElement logout = driver.findElement(By.linkText("Logoff"));                 
    logout.click();

    selenium.chooseOkOnNextConfirmation();
    selenium.getConfirmation();

    WebDriver driverInstance = ((WebDriverBackedSelenium) selenium).getUnderlyingWebDriver();

当测试到达：chooseOkOnNextConfirmation();控制台抛出错误：

Exception in thread "main" java.lang.UnsupportedOperationException: getConfirmation
at org.openqa.selenium.WebDriverCommandProcessor.execute(WebDriverCommandProcessor.java:278)
at org.openqa.selenium.WebDriverCommandProcessor.getString(WebDriverCommandProcessor.java:252)
at com.thoughtworks.selenium.DefaultSelenium.getConfirmation(DefaultSelenium.java:429)
at testscripts.Deployment.main(Deployment.java:149)

我已按照“seleniumhq”网站上的文档进行操作，但我不明白为什么它会抛出此错误，有什么想法吗？