Migrating from Firefox WebDriver to Marionette
You can use the same FirefoxProfile class, just add it to the DesiredCapabilities in the following way:
FirefoxProfile firefoxProfile = new FirefoxProfile();firefoxProfile.setPreference("browser.startup.homepage;about:home","about:blank");firefoxProfile.setPreference("startup.homepage_welcome_url","about:blank");firefoxProfile.setPreference("browser.usedOnWindows10.introURL","about:blank");firefoxProfile.setPreference("devtools.devedition.promo.url","");firefoxProfile.setPreference("xpinstall.signatures.required",false);DesiredCapabilities desiredCapabilities = DesiredCapabilities.firefox();desiredCapabilities.setCapability(FirefoxDriver.PROFILE, firefoxProfile);