Support SQuADv2 format for QA annotations (import & export)

[joshuaeckroth]

Format description: https://huggingface.co/datasets/squad_v2

[makseq]

Thanks for your feature request, we will discuss this with the team.

[joshuaeckroth]

Thanks. It strikes me SQuADv1 format is best because label-studio doesn't have a native way to say "no answer".

https://huggingface.co/datasets/squad

[makseq]

In LS you can keep annotation.result empty, doesn't it work for you? In this case LS exports the result witn empty array:

result: [ ]