    # File lib/fog/openstack/requests/compute/update_metadata.rb, line 20
            def update_metadata(collection_name, parent_id, metadata = {})

              if collection_name == "images" then
                if not list_images_detail.body['images'].detect {|_| _['id'] == parent_id}
                  raise Fog::Compute::OpenStack::NotFound
                end
              end

              if collection_name == "servers" then
                if not list_servers_detail.body['servers'].detect {|_| _['id'] == parent_id}
                  raise Fog::Compute::OpenStack::NotFound
                end
              end

              #FIXME join w/ existing metadata here
              response = Excon::Response.new
              response.body = { "metadata" => metadata }
              response.status = 200
              response

            end