How to retrieve the value of the return boolean of a REST service in Angularjs?

I have a Java / Jersey service that returns a Boolean pro for AngularJs. In my controller, I get the value of the return from the promise, but it returns me an Object. In other cases, as a return from a User entity, for example, it works fine, because I get the attributes of the returned object. Now when it returns only a boolean, how do I recover the value?

Below is an example I'm using:

Java service:

@POST
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
@Path("/verificaEmail")
public Boolean verificarEmail(String email){

    SimpleEntityManager simpleEntityManager = new SimpleEntityManager(persistenceUnitName);

    IUsuarioBusiness usuarioB = new UsuarioBusiness(simpleEntityManager);

    Boolean result = usuarioB.verificaEmail(email);

    return result;

}

Angular Controller:

this.cadastrarUsuario = function() {

  var usuario = {
    email: this.usuarioLogin.email,
    senha: this.usuarioLogin.senha,
    nome: this.usuarioLogin.nome
  }

  var verificaEmail = VerificaEmail.email(usuario.email);

  verificaEmail.$promise.then( 
    function success(result)
    {
      if (result) {
        $scope.erro = true;
        $scope.mensagemErro = "Email já existe!";
        $scope.mostraMensagem = true;
        $scope.setClasseErro();
      }
    })};

Service:

var servicoLogin = angular.module('servicoLogin', ['ngResource']);

servicoLogin.factory('VerificaEmail', ['$resource',
  function($resource){
    return $resource('http://localhost:8081/GameService/webserver/usuario/verificaEmail', {}, {
      email: {method:'POST'}
    });
  }]);

I'm just asking for help because I've already broken my head and I have not been able to solve this problem that seems to be simple.