namespace with desc not work

I am using rails 5.1.1 and ruby 2.4.1, grape and grape-swagger is the latest version

this following code did not generate swagger tag description,

resource :medicals, desc: "医生" do
  params do
    requires :phone
    requires :sms_code
    requires :password
  end
  post 'sign_up' do
    medical = Medical.new(phone: params[:phone], password: params[:password])

    if medical.save
      present_v medical, with: V1::Entities::Medical
    else
      resource_error!(medical)
    end
  end
end

Reproduce the example using Rails 5.1.1, Ruby 2.4.1, Grape, and the latest grape-swagger, then trace how the resource :medicals, desc: "医生" declaration becomes Swagger tags. Done means the generated Swagger documentation includes the resource description.