curl --request GET \
  --url https://{install}/api/plan/{boardId}/backlog \
  --header 'Authorization: Bearer <token>'

{
  "items": [
    {
      "id": "<string>",
      "containerId": "<string>",
      "containerName": "<string>",
      "key": "<string>",
      "name": "<string>",
      "status": "<string>",
      "workflowVerb": "<string>",
      "resourceType": "<string>",
      "resourceId": "<string>",
      "resourceName": "<string>",
      "workEstimate": 123,
      "boardId": "<string>",
      "cycleId": "<string>"
    }
  ],
  "page": 123,
  "pageSize": 123,
  "totalCount": 123,
  "warnings": [
    "<string>"
  ]
}