Retrieve roles for user with user objectID in Cloud Code

Question

I'm trying to retrieve roles for a desired user where I know if objectId.

exports.User.getUserRole = function(userId, success, error)
{
  Parse.Cloud.useMasterKey();

  console.log("getUserRole method");

  var query = new Parse.Query(Parse.User);

  query.
  equalTo("objectId", userId)
  .find({
    success: function(user){
      console.log("SUCCESS 1");
      console.log(user);

      var queryRole = new Parse.Query(Parse.Role);

      queryRole
      .equalTo("users", user)
      .find({success: function(roles){
        console.log("SUCCESS 2");
        success(roles);
      },
      error: function(_errorRole){
        console.log("FAIL 2");
        console.log(_errorRole);
        error(_errorRole);
      }
    });
  },
  error: function(_error){
    console.log("FAIL 1");
    error(_error);
  }
});

But I've this strange error in the CloudCode logs:

FAIL 2 // My console.log

{"code":102,"message":"equality needs a value instead of [map[__type:Pointer className:_User objectId:qjsmwxQ4KQ]] "}