Termsvector of an element of array

[tim2020work2]

How do I view terms vector of a field in an element of array?

API _termvectors accept input "fields". i.e

  "fields" : ["msg"],
}

If I want to view term vector of an element of array, the following does not work

  "fields" : ["object.array[0].msg"],
}

with the following response

{
    "_id": "63772d17e00e205f040903f4",
    "_version": 7173960264797126656,
    "found": true,
    "took": 0,
    "term_vectors": {}
}