- Introduce the field `CustomRecords` to the type `UpdateFulfillHtlc`. - Encode and decode the new field into the `ExtraData` field of the `update_fulfill_htlc` wire message. - Empty `ExtraData` field is set to `nil`.
- Introduce the field `CustomRecords` to the type `UpdateFulfillHtlc`. - Encode and decode the new field into the `ExtraData` field of the `update_fulfill_htlc` wire message. - Empty `ExtraData` field is set to `nil`.