curl --request POST \
  --url https://api.hubapi.com/marketing/v3/marketing-events/events/upsert \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "inputs": [
    {
      "startDateTime": "2023-11-07T05:31:56Z",
      "customProperties": [
        {
          "sourceId": "",
          "selectedByUser": false,
          "sourceLabel": "",
          "sourceUpstreamDeployable": "<string>",
          "source": "",
          "updatedByUserId": 123,
          "persistenceTimestamp": 123,
          "sourceMetadata": "",
          "dataSensitivity": "",
          "sourceVid": "",
          "unit": "",
          "requestId": "",
          "isEncrypted": false,
          "name": "",
          "useTimestampAsPersistenceTimestamp": true,
          "value": "",
          "selectedByUserTimestamp": 123,
          "timestamp": 123,
          "isLargeValue": true
        }
      ],
      "externalAccountId": "<string>",
      "eventCancelled": true,
      "eventOrganizer": "<string>",
      "eventUrl": "<string>",
      "externalEventId": "<string>",
      "eventDescription": "<string>",
      "eventName": "<string>",
      "eventType": "<string>",
      "eventCompleted": true,
      "endDateTime": "2023-11-07T05:31:56Z"
    }
  ]
}'

{
  "completedAt": "2023-11-07T05:31:56Z",
  "numErrors": 123,
  "requestedAt": "2023-11-07T05:31:56Z",
  "startedAt": "2023-11-07T05:31:56Z",
  "links": {},
  "results": [
    {
      "eventOrganizer": "<string>",
      "eventUrl": "<string>",
      "eventType": "<string>",
      "eventCompleted": true,
      "endDateTime": "2023-11-07T05:31:56Z",
      "createdAt": "2023-11-07T05:31:56Z",
      "startDateTime": "2023-11-07T05:31:56Z",
      "customProperties": [
        {
          "sourceId": "",
          "selectedByUser": false,
          "sourceLabel": "",
          "sourceUpstreamDeployable": "<string>",
          "source": "",
          "updatedByUserId": 123,
          "persistenceTimestamp": 123,
          "sourceMetadata": "",
          "dataSensitivity": "",
          "sourceVid": "",
          "unit": "",
          "requestId": "",
          "isEncrypted": false,
          "name": "",
          "useTimestampAsPersistenceTimestamp": true,
          "value": "",
          "selectedByUserTimestamp": 123,
          "timestamp": 123,
          "isLargeValue": true
        }
      ],
      "eventCancelled": true,
      "eventDescription": "<string>",
      "eventName": "<string>",
      "id": "<string>",
      "objectId": "<string>",
      "updatedAt": "2023-11-07T05:31:56Z"
    }
  ],
  "errors": [
    {
      "subCategory": "",
      "context": "",
      "links": "",
      "id": "",
      "category": "",
      "message": "",
      "errors": "",
      "status": ""
    }
  ],
  "status": "PENDING"
}