curl --request PATCH \
  --url https://prod.featherhq.com/api/v1/calendars/{calendarId}/connections/{connectionId} \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '
{
  "externalCalendarId": "<string>"
}
'

{
  "id": "<string>",
  "calendarId": "<string>",
  "accountEmail": "<string>",
  "externalCalendarId": "<string>",
  "invalid": true,
  "createdAt": "<string>",
  "updatedAt": "<string>"
}