def request_params(params = {})
      default_request_params.merge(params) do |key, oldval, newval|
        key == :headers ? oldval.merge(newval) : newval
      end
    end
def request_params(params = {})
      default_request_params.merge(params) do |key, oldval, newval|
        key == :headers ? oldval.merge(newval) : newval
      end
    end
@param [ Hash ] params

 @return [ Hash ]