ReadonlyactionOptional ReadonlydeliveryOptional Readonlydeliverykey of an existing Delivery.
Either `deliveryId` or `deliveryKey` must be provided.
Optional ReadonlyfieldsSets the Custom Fields fields for the Delivery.
Optional ReadonlytypeDefines the Type that extends the Delivery with Custom Fields. If absent, any existing Type and Custom Fields are removed from the Delivery.
idof an existing Delivery.