# File lib/googleauth/default_credentials.rb, line 77
      def self.determine_creds_class json_key_io
        json_key = MultiJson.load json_key_io.read
        key = "type"
        raise "the json is missing the '#{key}' field" unless json_key.key? key
        type = json_key[key]
        case type
        when "service_account"
          [json_key, ServiceAccountCredentials]
        when "authorized_user"
          [json_key, UserRefreshCredentials]
        else
          raise "credentials type '#{type}' is not supported"
        end
      end