Metadata fields managed internally by the library: the guid, timestamps and
local sync state. These are automatically set on add_credit_card and
updated on operations like touch and update_credit_card. Not included in
UpdatableCreditCardFields; use add_credit_card_with_meta when importing
records that already have metadata.
A credit card together with its metadata, passed to
add_credit_card_with_meta and update_credit_card_with_meta when importing
a record from another store.
A bulk insert result entry, returned per input record by
add_many_credit_cards_with_meta so that one record failing does not abort
the batch. Note that although the success case is much larger than the error
case, this is negligible in real life, as we expect a very small
success/error ratio.