curl --request POST \
  --url https://app.herondata.io/api/end_user_entities/{entity_heron_id}/attributes \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '{
  "attribute_description": "<string>",
  "attribute_name": "<string>",
  "attribute_type": "float",
  "display_order": 123,
  "is_dedupe_key": false,
  "reconciliation_config": {},
  "reconciliation_strategy": "sort_order"
}'

{
  "attribute_description": "<string>",
  "attribute_name": "<string>",
  "attribute_type": "float",
  "display_order": 123,
  "heron_id": "<string>",
  "is_dedupe_key": false,
  "reconciliation_config": {},
  "reconciliation_strategy": "sort_order"
}