The following example shows how to use the varargs parameter in the setDriver method, which is called optPreferences. This is the setDriver method so far, from what we have built:

@SafeVarargs
public final void setDriver(String browser,
                            String environment,
                            String platform,
                            Map<String, Object>... optPreferences)
                            throws Exception {

    DesiredCapabilities caps = null;
    String localHub = "http://127.0.0.1:4723/wd/hub";
    String getPlatform = null;

    switch (browser) {
        case "firefox":
            caps = DesiredCapabilities.firefox();
            FirefoxProfile ffProfile = new FirefoxProfile();

            ffProfile.setPreference("browser.autofocus",
                                     true);
            caps.setCapability(FirefoxDriver.PROFILE,
                               ffProfile);
            caps.setCapability("marionette",
                                true);
            System.setProperty("webdriver.gecko.driver",
            "gecko_driver_windows_path/geckodriver.exe");

            if ( optPreferences.length > 0 ) {
                processFFProfile(ffProfile, optPreferences);
            }

            webDriver.set(new FirefoxDriver(caps));
            break;
        case "chrome":
            caps = DesiredCapabilities.chrome();
            ChromeOptions chOptions = new ChromeOptions();

            Map<String, Object> chromePrefs =
                                new HashMap<String, Object>();
            chromePrefs.put("credentials_enable_service",
                             false);
            chOptions.setExperimentalOption("prefs",
                                             chromePrefs);
            chOptions.addArguments("--disable-plugins",
                                   "--disable-extensions",
                                   "--disable-popup-blocking");
            caps.setCapability(ChromeOptions.CAPABILITY,
                               chOptions);
            caps.setCapability("applicationCacheEnabled",
                               false);
            System.setProperty("webdriver.chrome.driver",
            "chrome_driver_windows_path/chromedriver.exe");

            if ( optPreferences.length > 0 ) {
                processCHOptions(chOptions, optPreferences);
            }

            webDriver.set(new ChromeDriver(caps));
            break;
        case "internet explorer":
            caps = DesiredCapabilities.internetExplorer();

            InternetExplorerOptions ieOpts =
                    new InternetExplorerOptions();

            ieOpts.requireWindowFocus();
            ieOpts.merge(caps);
            caps.setCapability("requireWindowFocus",
                                true);
            System.setProperty("webdriver.ie.driver",
            "ie_driver_windows_path/IEDriverServer.exe");

            if ( optPreferences.length > 0 ) {
                processDesiredCaps(caps, optPreferences);
            }

            webDriver.set(new InternetExplorerDriver(caps));
            break;
    }

    // etc...
}