Clean Java development

@Path("/hello/{name}")
public class HelloResource {
    @Inject
    private GreeterService greeterService;

    @GET
    @Produces(MediaType.TEXT_HTML)
    public String hello(@PathParam("name") String name) {
        return greeterService.sayHello(name);
    }

    @Service
    interface GreeterService {
        String sayHello(String name);
    }

    static class HtmlGreeterService implements GreeterService {
        @Override
        public String sayHello(String name) {
            return "<h1>Hello " + name + "!</h1>";
        }
    }
}