Estou recebendo uma exception na hora de chamar o autentica e revisei o código todo e não consigo encontra.
javax.servlet.ServletException: net.vidageek.mirror.exception.ReflectionProviderException: Could not invoke method autentica
    br.com.caelum.vraptor.VRaptor.doFilter(VRaptor.java:120)
package br.com.caelum.vraptor.controller;
import br.com.caelum.vraptor.Controller;
import br.com.caelum.vraptor.Get;
import br.com.caelum.vraptor.Post;
import br.com.caelum.vraptor.Result;
import br.com.caelum.vraptor.dao.UsuarioDao;
import br.com.caelum.vraptor.model.Usuario;
import br.com.caelum.vraptor.validator.I18nMessage;
import br.com.caelum.vraptor.validator.Validator;
@Controller
public class LoginController {
    private final UsuarioDao dao;
    private final Result result;
    private final Validator validator;
    private final UsuarioLogado usuarioLogado;
    public LoginController(UsuarioDao dao, Result result, Validator validator, UsuarioLogado usuarioLogado) {
        this.dao = dao;
        this.result = result;
        this.validator = validator;
        this.usuarioLogado = usuarioLogado;
    }
    @Deprecated
    public LoginController() {
        this(null, null, null, null);
    }
    @Get
    public void formulario( ) {    
    }
    @Post
    public void autentica(Usuario usuario) {
        if(!dao.existe(usuario)){
            validator.add(new I18nMessage("login", "login.invalido"));
            validator.onErrorUsePageOf(this).formulario();
        }
        usuarioLogado.setUsuario(usuario);
        result.redirectTo(ProdutoController.class).lista();
    }
}
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<link rel="stylesheet" type="text/css" href="../bootstrap/css/bootstrap.css">
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Formulário de login</title>
</head>
<body>
    <div class="conteiner">
        <form class="form-signin" action="<c:url value='/login/autentica'/>" method="post">
        <h2 class="form-signin-heading">Faça login para acessar o VRaptor-produtos</h2>
            <input type="text" class="form-control" name="usuario.nome" placeholder="Nome"/> 
            <input type="password" class="form-control" name="usuario.senha" placeholder="Senha"/>
            <button class="btn btn-lg btn-primary btn-block" type="submit">Login</button>
        </form>
        <c:if test="${not empty errors }">
            <div class="alert alert-danger">
                <c:forEach var="error" items="${errors}">
                    ${error.category } - ${error.message }<br>
                </c:forEach>
            </div>
        </c:if>
    </div>
</body>
</html>