```ruby
module UTF8Cleaner
  class Railtie < Rails::Railtie
    initializer "utf8-cleaner.insert_middleware" do |app|
      app.config.middleware.insert_before 0, "UTF8Cleaner::Middleware"
    end
  end
end```

Remove Rails 5 / Rack deprecation warning
user
```ruby
module UTF8Cleaner
  class Railtie < Rails::Railtie
    initializer "utf8-cleaner.insert_middleware" do |app|
      app.config.middleware.insert_before 0, UTF8Cleaner::Middleware
    end
  end
end
```
assistant