curl --request GET \
  --url https://api.smokeball.com/tasks/{taskId}/subtasks \
  --header 'Authorization: <api-key>' \
  --header 'x-api-key: <api-key>'

{
  "id": "<string>",
  "href": "<string>",
  "relation": "<string>",
  "method": "GET",
  "self": {
    "id": "<string>",
    "href": "<string>",
    "relation": "<string>",
    "method": "GET"
  },
  "value": [
    {
      "id": "<string>",
      "href": "<string>",
      "relation": "<string>",
      "method": "GET",
      "self": {
        "id": "<string>",
        "href": "<string>",
        "relation": "<string>",
        "method": "GET"
      },
      "parentTask": {
        "id": "<string>",
        "href": "<string>",
        "relation": "<string>",
        "method": "GET"
      },
      "createdBy": {
        "id": "<string>",
        "href": "<string>",
        "relation": "<string>",
        "method": "GET"
      },
      "completedBy": {
        "id": "<string>",
        "href": "<string>",
        "relation": "<string>",
        "method": "GET"
      },
      "lastUpdatedBy": {
        "id": "<string>",
        "href": "<string>",
        "relation": "<string>",
        "method": "GET"
      },
      "subject": "Confer with Mary",
      "completedDate": "2020-02-15T13:00:00Z",
      "completedDateOnly": "2020-02-15T00:00:00",
      "createdDate": "2020-02-15T13:00:00Z",
      "createdDateOnly": "2020-02-15T00:00:00",
      "isCompleted": false,
      "isDeleted": false,
      "lastUpdated": 637847425252027400
    }
  ]
}