curl --request GET \
  --url https://sandbox.api.btdx.io/event-groups/by-reference/{source}/{reference} \
  --header 'authorization: <authorization>'

{
  "_meta": {
    "_count": 123,
    "_page": {
      "_pageNumber": 123,
      "_pageSize": 123,
      "_totalElements": 123,
      "_totalPages": 123
    }
  },
  "eventGroups": [
    {
      "id": "<string>",
      "externalReferences": {
        "_ref": "<string>",
        "_ids": [
          "<string>"
        ]
      },
      "name": "<string>",
      "subcategory": {
        "_ref": "<string>",
        "_ids": [
          "<string>"
        ]
      },
      "createdAt": "2023-11-07T05:31:56Z",
      "modifiedAt": "2023-11-07T05:31:56Z"
    }
  ],
  "externalReferences": [
    {
      "id": 123,
      "source": "<string>",
      "externalReference": "<string>"
    }
  ],
  "subcategories": [
    {
      "id": "<string>",
      "name": "<string>",
      "category": {
        "_ref": "<string>",
        "_ids": [
          "<string>"
        ]
      }
    }
  ],
  "categories": [
    {
      "id": "<string>",
      "name": "<string>"
    }
  ]
}