OpenQA.Selenium.Firefox，想要安装Firfefox Extension XPI，什么也没有发生

Question

我要安装的XPI路径是

#region VARS
const string adblock = @"C:\pm\Sources\Extension\adblock_plus-3.4.2-an+fx.xpi";

然后我执行以下操作，firefox中什么也没有发生，没有加载/安装扩展名。

const string adblock = @"C:\pm\Sources\Extension\adblock_plus-3.4.2-an+fx.xpi";
FirefoxProfile profile = new FirefoxProfile();
profile.AddExtension(adblock);
FirefoxOptions ffoptions = new FirefoxOptions(); 
IWebDriver driver = new FirefoxDriver(ffoptions);

不接受：无法从FirefoxProfile转换为FirefoxOptions：

const string adblock = @"C:\pm\Sources\Extension\adblock_plus-3.4.2-an+fx.xpi";
FirefoxProfile profile = new FirefoxProfile();
profile.AddExtension(adblock);
IWebDriver driver = new FirefoxDriver(profile);