Empty output/answer in TriviaQA test set (both in 'kilt_tasks' and 'trivia_qa')
cc @yjernite is this expected ? Yes: TriviaQA has a private test set for the leaderboard [here](https://competitions.codalab.org/competitions/17208)

For the KILT training and validation portions, you need to link the examples from the TriviaQA dataset as detailed here:
https://github.com/huggingface/datasets/blob/master/datasets/kilt_tasks/README.md Oh ok, I guess I read the paper too fast 😅, thank you for your answer!
# The issue

It's all in the title, it appears to be fine on the train and validation sets.

Is there some kind of mapping to do like for the questions (see https://github.com/huggingface/datasets/blob/master/datasets/kilt_tasks/README.md) ? 

# How to reproduce
```py
from datasets import load_dataset
kilt_tasks = load_dataset("kilt_tasks")
trivia_qa = load_dataset('trivia_qa', 'unfiltered.nocontext')
# both in "kilt_tasks"
In [18]: any([output['answer'] for output in kilt_tasks['test_triviaqa']['output']])                                                                                                                        
Out[18]: False
# and "trivia_qa"
In [13]: all([answer['value'] == '<unk>' for answer in trivia_qa['test']['answer']])                                                                                                                        
Out[13]: True
# appears to be fine on the train and validation sets.
In [14]: all([answer['value'] == '<unk>' for answer in trivia_qa['train']['answer']])                                                                                                                       
Out[14]: False

In [15]: all([answer['value'] == '<unk>' for answer in trivia_qa['validation']['answer']])                                                                                                                  
Out[15]: False

In [16]: any([output['answer'] for output in kilt_tasks['train_triviaqa']['output']])                                                                                                                       
Out[16]: True

In [17]: any([output['answer'] for output in kilt_tasks['validation_triviaqa']['output']])                                                                                                                  
Out[17]: True

```