    # File lib/action_controller/http_authentication.rb, line 220
          def encode_credentials(http_method, credentials, password, password_is_ha1)
            credentials[:response] = expected_response(http_method, credentials[:uri], credentials, password, password_is_ha1)
            "Digest " + credentials.sort_by {|x| x[0].to_s }.inject([]) {|a, v| a << "#{v[0]}='#{v[1]}'" }.join(', ')
          end