Use nested value from record as key in Kafka

[#1]

Hi guys,

I have some problem with public data on Kafka. I have record to public like this:

{
"name": "Jess",
"surname": "Stone",
 "data": {
"mail": "j.stone@gmail.com",
"class": "5",
  "address": {
  "country": "Brasil",
  "city": "Rio de Janeiro"
 }
},
"anotherData": {
"sex": "female",
"code": "1220"
}
}

I need set code value as key so I set it like 

Message Key Field sex

But it doesn't works, i think it is possible that it doesn't work because this value is nested-when I set for example name it works. Maybe you know how can I set these nested value from this record to Message Key Field? I tried something like this: anotherData.sex but it doesn't work too...

[#2]

Have you considered using EvaluateJSONPath to extract the value as a FlowFile attribute and then use that for your key when publishing to Kafka?