ReadonlyactionOptional ReadonlyfieldsObject containing the Custom Fields fields for the PaymentMethod.
Required if at least one Custom Field is defined as required in the `fieldDefinitions` of the referenced [Type](ctp:api:type:Type).
Optional ReadonlytypeDefines the Type that extends the PaymentMethod with Custom Fields. If absent, any existing Type and Custom Fields are removed from the PaymentMethod.
Adding or updating a Custom Type on a PaymentMethod generates the PaymentMethodCustomTypeSet Message, removing one generates the PaymentMethodCustomTypeRemoved Message.