Subscription items update without proration billing mode

{
  "error": {
    "type": "request_error",
    "code": "subscription_items_update_missing_proration_billing_mode",
    "detail": "proration_billing_mode is required when updating subscription items",
    "documentation_url": "https://developer.paddle.com/errors/subscriptions/subscription_items_update_missing_proration_billing_mode"
  },
  "meta": {
    "request_id": "00000000-0000-0000-0000-000000000000"
  }
}