Método Post em /auth retorna Bad Request

Não tem corpo retornado e nem acontece erro no console do Eclipse, então fiquei meio confuso do que pode ser. Se faço um parseLong do expiration ele retorna erro 500.

package br.com.alura.forum.config.security;

import java.util.Date;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.core.Authentication;
import org.springframework.stereotype.Service;

import br.com.alura.forum.modelo.Usuario;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;

@Service
public class TokenService {

    @Value("${forum.jwt.expiration}")
    private String expiration;
    @Value("${forum.jwt.secret}")
    private String secret;

    public String gerarToken(Authentication authentication) {
        Usuario logado = (Usuario) authentication.getPrincipal();
        Date hoje = new Date();
        Date dataExpiracao = new Date(hoje.getTime() + expiration);


        return Jwts.builder()
                .setIssuer("API treinamento Compasso")
                .setSubject(logado.getId().toString())
                .setIssuedAt(hoje)
                .setExpiration(dataExpiracao)
                .signWith(SignatureAlgorithm.HS256, secret)
                .compact();
    }

}

package br.com.alura.forum.controller;

import javax.naming.AuthenticationException;
import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import br.com.alura.forum.config.security.TokenService;
import br.com.alura.forum.controller.form.LoginForm;

@RestController
@RequestMapping("/auth")
public class AutenticacaoController {

    @Autowired
    private AuthenticationManager authManager;

    @Autowired
    private TokenService tokenService;

    @PostMapping
    public ResponseEntity<?> autenticar(@RequestBody @Valid LoginForm form){
        UsernamePasswordAuthenticationToken dadosLogin = form.converter();

        try {
            Authentication authentication = authManager.authenticate(dadosLogin);
            String token = tokenService.gerarToken(authentication);

            return ResponseEntity.ok().build();
        } catch (Exception e) {
            return ResponseEntity.badRequest().build();
        }
    }

}

package br.com.alura.forum.config.security;

import java.util.Optional;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.stereotype.Service;

import br.com.alura.forum.modelo.Usuario;
import br.com.alura.forum.repository.UsuarioRepository;

@Service
public class AutenticacaoService implements UserDetailsService {

    @Autowired
    private UsuarioRepository repository;

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {

        Optional<Usuario> usuario = repository.findByEmail(username);

        if(usuario.isPresent()) {
            return usuario.get();
        } else {
            throw new UsernameNotFoundException("Dados inválidos!");
        }
    }

}