can not create documentation without namespace

I am trying to create documentation for this

    desc 'Returns your public timeline.' do
    summary 'summary'
    detail 'more details'
    named 'My named route'
    headers XAuthToken: {
              description: 'Validates your identity',
              required: true
            },
            XOptionalHeader: {
              description: 'Not really needed',
              required: false
            }
    hidden false
    deprecated false
    is_array true
    nickname 'nickname'
    produces ['application/json']
    consumes ['application/json']
    tags ['tag1', 'tag2']
  end
  
  post '/:name.json' do

  end

As I understand It does not work with routes like /:test and only works with namespaces or resources

Reproduce the Ruby Grape example with a parameterized route such as /:test, then compare documentation generation with the namespace or resource cases described in the issue. Trace the route documentation entry point and verify that the generated Swagger or OpenAPI documentation includes the route without requiring a namespace or resource.