Plot the pr curve for squadv2

The evaluate library allows us to plot the pr curve if a na_prob.json file is provided (
evaluate/ at main 路 huggingface/evaluate 路 GitHub, line 4).

I can鈥檛 find any information on how to generate this na_prob.json file using the trainer (transformers/ at main 路 huggingface/transformers 路 GitHub). Can the eval_nbest_predictions.json file be used for this purpose?