Post IP address with custom fields via REST API

[The-Astiks]

I want to POST an IP with some custom fields.
SwaggerUI generated following request:

curl -X 'POST' \
  'https://172.21.0.242/api/ipam/ip-addresses/' \
  -H 'accept: application/json' \
  -H 'Content-Type: multipart/form-data' \
  -H 'X-CSRFTOKEN: lV9H5gy3HNkF2XakAfolGs3F5NX39L6NcJiANgr43FyKaA2w5f3two1vdQm8FnzV' \
  -F 'custom_fields={
  "test1": "123",
  "test2": "456"
}' \
  -F 'address=1.1.1.1/24'

But in response received 400 Error: Bad Request:

{
  "custom_fields": [
    "Invalid data format. Custom field data must be passed as a dictionary mapping field names to their values."
  ]
}

Custom_fields value was filled this way:

Where did I go wrong?

[chris240189]

what are the types and names of the custom fields you are trying to write to?