@type t() :: %Merchant.WebhookEvent{
  dispute_id: (String.t() | nil) | nil,
  event: String.t() | nil,
  merchant_order_ext_ref: (String.t() | nil) | nil,
  order_id: (String.t() | nil) | nil,
  payout_id: (String.t() | nil) | nil
}