@CurrentTimestamp

New annotation "@CurrentTimestamp" should inject the current timestamp of a transaction into a data field.

The annotation will guarantee that at the transaction start the timestamp is produced once, so all uses of the annotation within the same transaction will guarantee to inject the same timestamp value.

This is another essential business need, as sometimes transactions run rather long, but all written data shall have synchronized timestamps.

No files, tests, or entry points are named. Start by reviewing the persistence project's existing annotation and transaction timestamp behavior; done means defining @CurrentTimestamp so one transaction-start timestamp is consistently injected into all annotated data fields.

Written by the indexing model from the issue text.