Não cai no método detalhar

Ao chamar a url http://localhost:8080/topicos/3 sempre cai no método lista

package br.com.alura.forum.controller;

import java.net.URI;
import java.util.List;

import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.util.UriComponentsBuilder;

import br.com.alura.forum.controller.form.TopicoForm;
import br.com.alura.forum.dto.DetalhesTopicoDto;
import br.com.alura.forum.dto.TopicoDto;
import br.com.alura.forum.modelo.Topico;
import br.com.alura.forum.repository.CursoRepository;
import br.com.alura.forum.repository.TopicoRepository;

@RestController("/topicos")
public class TopicosController {

    @Autowired
    private TopicoRepository topicoRepository;

    @Autowired
    private CursoRepository cursoRepository;

    @GetMapping
    public List<TopicoDto> lista(String nomeCurso){
        if(nomeCurso == null) {
            List<Topico> topicos = topicoRepository.findAll();
            return TopicoDto.converter(topicos);
        }else {
            List<Topico> topicos = topicoRepository.findByCursoNome(nomeCurso);
            return TopicoDto.converter(topicos);
        }
    }

    @PostMapping
    public ResponseEntity<TopicoDto> cadastrar(@RequestBody @Valid TopicoForm form, UriComponentsBuilder uriBuilder) {
        Topico topico = form.converter(cursoRepository);
        topicoRepository.save(topico);

        URI uri = uriBuilder.path("/topicos/{id}").buildAndExpand(topico.getId()).toUri();
        return ResponseEntity.created(uri).body(new TopicoDto(topico));
    }

    @GetMapping("/{id}")
    public DetalhesTopicoDto detalhar(@PathVariable Long id){
        Topico topico = topicoRepository.getOne(id);
        return new DetalhesTopicoDto(topico);

    }
}