Feature req: Labels in multiple languages in REST API suggest method(s)

[osma]

We received this feature request for the Finto AI API, which is basically the Annif API:

"Is it possible to have your Finto AI API return all available language equivalents for a given term? Currently, for example, when using YSO EN, it only returns the term in the English language (or the language specified as a parameter), even though there are likely other translations available. The desired functionality would be for the API to return all available equivalents for a term across all supported languages. For example, if we send a project request using yso-en and specify Finnish (fi), Swedish (sv), and English (en) as the desired languages, we would like to receive suggestions for the term in all three of those languages within a single request."

(machine translated from the original Finnish)

One question is how the response data would look like. Currently the suggest response looks like this:

{
  "results": [
    {
      "uri": "http://example.org/subject1",
      "label": "Archaeology",
      "notation": "42.42",
      "score": 0.85
    }
  ]
}

Instead of a single string value for the label field, we could return something like:

      "label": {
          "en": "archaeology",
          "fi": "arkeologia",
          "sv": "arkeologi"
      }

Another option would be to use several language-specific fields like label_en , label_fi, label_sv.