As of OGM-122, `Calendar` properties are mapped as a timestamp, loosing any time zone information. I.e. upon read-back we don't know the TZ to convert to. Instead we may provide an option to persist such properties as formatted Strings.

If we decide to wait for a future native Cassandra datatype with TZ support, we should log a warning / add a note to the docs about the loss of information in the current approach.