Nested key claim name

Questions
#1

I want to know how one can use nested jwt payload in kong?
imagine I have the following payload:

{
    'level1': {
        'level2': 'something',
    },
}

now if I would like to say that my key_claim_name is going to be level1.level2 it says that’s not possible through the following error:

{
    "message": "No mandatory 'level1.level2' in claims"
}