curl --request POST \
  --url https://api.hubapi.com/crm/v3/imports/ \
  --header 'Content-Type: multipart/form-data' \
  --header 'private-app: <api-key>' \
  --form 'importRequest=<string>' \
  --form files=@example-file

{
  "importTemplate": {
    "templateType": "admin_defined",
    "templateId": 123
  },
  "createdAt": "2023-11-07T05:31:56Z",
  "metadata": {
    "counters": {},
    "fileIds": [
      "<string>"
    ],
    "objectLists": [
      {
        "listId": "<string>",
        "objectType": "<string>"
      }
    ]
  },
  "importRequestJson": {},
  "importSource": "API",
  "importName": "<string>",
  "state": "STARTED",
  "id": "<string>",
  "optOutImport": true,
  "mappedObjectTypeIds": [
    "<string>"
  ],
  "updatedAt": "2023-11-07T05:31:56Z"
}