curl --request GET \
  --url https://app.herondata.io/api/end_user_entities \
  --header 'x-api-key: <api-key>'

[
  {
    "display_order": 123,
    "entity_attributes": [
      {
        "attribute_description": "<string>",
        "attribute_name": "<string>",
        "attribute_sources": [
          {
            "heron_id": "<string>",
            "sort_order": 123,
            "source_config": {},
            "source_type": "parsed_end_user_file"
          }
        ],
        "attribute_type": "float",
        "display_order": 123,
        "heron_id": "<string>",
        "is_dedupe_key": false,
        "reconciliation_config": {},
        "reconciliation_strategy": "sort_order"
      }
    ],
    "entity_description": "<string>",
    "entity_name": "<string>",
    "heron_id": "<string>",
    "is_list": true,
    "saved_query_heron_id": "<string>"
  }
]