Avro Records with Unknown Key Names and Quantity but Known Values - avro

Question

I am looking to convert JSON to Avro without altering the shape of the data
A nested field in the JSON contains a variable number of keys, which are never known in advance. The record that branches off of each of these unknown nodes however is of known, well-defined shape.
An example of this input data is as shown below
{
"customers": {
"paul_ince": {
"name": "Mr Paul Ince",
"age": 54
},
"kim_kardashian": {
"name": "Ms Kim Kardashian",
"age": 41
},
"elon_musk": {
"name": "Elon Musk, Technoking of Tesla",
"age": 50
}
}
Now it would be more avro friendly of course to have customers lead to an array of the form
{
"customers": [
{
"customer_name": "paul_ince",
"name": "Mr Paul Ince",
"age": 54
},
{
...
}
]
}
But this would violate my constraint that the shape of the input data be unchanged.
This problem seems to manifest itself frequently if I rely on data from external sources or scrapes, or preexisting data that was never created for Avro.
In my head, the schema would look something like the below,
{
"fields": [
{
"name": "customers",
"type": {
"type": "record",
"name": "customers",
"fields": [
{
"name": $customer_name,
"type": {
"type": "record",
"name": $customer_name,
"fields": [
{
"name": "name",
"type": "string",
},
{
"name": "age",
"type": "int"
}
]
}
}
]
}
}
]
}
where $customer_name is an assignment value, defined on read. Just asking the question it feels like this violates fundamental avro but I must use Avro and I strongly desire to maintain the input shape of the data. It would be highly impractical to modify this, not least given how frequently this problem appears and how large and varied the data I need to transfer from JSON to Avro is