class Excon::Connection

def valid_middleware_keys(middlewares)
  middlewares.flat_map do |middleware|
    if middleware.respond_to?(:valid_parameter_keys)
      middleware.valid_parameter_keys
    else
      Excon.display_warning(
        "Excon middleware #{middleware} does not define #valid_parameter_keys"
      )
      []
    end
  end
end