The @app.Group annotation is used to define a group of routes, interceptors and error handlers:

@app.Group("/user")
class UserService {

  @app.Route("/find")
  findUser(@app.QueryParam("n") String name,
           @app.QueryParam("c") String city) {
    // ...
  }

  @app.Route("/add", methods: const [app.POST])
  addUser(@app.Body(app.JSON) Map json) {
    // ...
  }
}

The prefix defined with the @app.Group annotation, will be prepended in every route and interceptor inside the group. If you need to directly bind to the group's path, you can use the @DefaultRoute annotation:

@app.Group("/user")
class UserService {

  @app.DefaultRoute()
  getUser() {
    // ...
  }

  @app.DefaultRoute(methods: const[app.POST])
  postUser(@app.Body(app.JSON) Map user) {
    // ...
  }

  @app.Route("/:id")
  getUserById(String id) {
   // ...
  }
}