Required params at the top level namespace, is this possible?

My code is currently like this:

    namespace :top_level do
      namespace :child_one do
        params do
          requires :token, :type => String
          requires :id, :type => String
        end

        mount V1::Controllers::ChildOneController
      end

      namespace :child_two do
        params do
          requires :token, :type => String
          requires :id, :type => String
          requires :name, :type => String
          requires :description, :type => String
        end

        mount V1::Controllers::ChildTwoController
      end

As both child_one and child_two routes require token and id, is it possible to move them up to the top_level namespace? I tried the following but it doesn't seem to work:

    namespace :top_level do
      params do
        requires :token, :type => String
        requires :id, :type => String
      end

      namespace :child_one do
        mount V1::Controllers::ChildOneController
      end

      namespace :child_two do
        params do
          requires :name, :type => String
          requires :description, :type => String
        end

        mount V1::Controllers::ChildTwoController
      end

Start by reproducing the nested namespace and params-block examples from the issue in a local Grape API. Read the namespace and parameter-validation entry points to determine whether parent parameters are inherited; done means establishing the supported behavior or documenting that top-level required parameters cannot apply to both mounted child routes.