curl --request POST \
  --url https://api.{tenant}.getomneo.com/api/v3/appointment-definitions/{appointmentDefinition}/staff \
  --header 'Content-Type: application/json' \
  --data '
{
  "staff_id": "<string>",
  "is_active": true
}
'

{
  "data": {
    "id": 123,
    "appointment_definition_id": 123,
    "staff_id": "<string>",
    "is_active": true,
    "staff": {
      "id": "<string>",
      "first_name": "<string>",
      "last_name": "<string>",
      "email": "<string>",
      "mobile_phone": "<string>",
      "normal_hours": [
        {
          "id": "<string>",
          "day_of_week": "<string>",
          "available_from": "<string>",
          "available_until": "<string>",
          "is_closed": "<string>"
        }
      ],
      "special_hours": [
        {
          "id": "<string>",
          "name": "<string>",
          "is_repeating": "<string>",
          "available_from": "<string>",
          "available_until": "<string>",
          "start_at": "<string>",
          "end_at": "<string>"
        }
      ]
    },
    "created_at": "<string>",
    "updated_at": "<string>"
  }
}