# File lib/googleauth/user_refresh.rb, line 80
      def self.read_json_key json_key_io
        json_key = MultiJson.load json_key_io.read
        wanted = %w[client_id client_secret refresh_token]
        wanted.each do |key|
          raise "the json is missing the #{key} field" unless json_key.key? key
        end
        json_key
      end