class Selenium::WebDriver::Firefox::Options

def as_json(*)
  opts = @options
  opts[:profile] = @profile.encoded if @profile
  opts[:args] = @args if @args.any?
  opts[:binary] = @binary if @binary
  opts[:prefs] = @prefs unless @prefs.empty?
  opts[:log] = {level: @log_level} if @log_level
  {KEY => opts}
end