When set, the response additionally populates 'retentionPeriod'
sibling fields (typed as DurationInUnit, carrying both unit and
duration) on the policy and its copy / extended-retention
sub-policies. The requested unit (Days or Minutes) is echoed in each
populated DurationInUnit.Unit and the duration field on the same
DurationInUnit carries the re-expressed whole-number count in that
unit (DaysToKeep values multiplied by 1440 for Minutes; NumSecsToKeep
floored by 60 for Minutes and 86400 for Days).
The existing whole-number retention fields keep their original names
and units regardless of the requested unit:
DaysToKeep / DaysToKeepLog / DaysToKeepSystem stay in days, even
when Minutes was requested. They are not renamed and not
converted; they remain the source of truth.
NumSecsToKeep stays in seconds.
Only the new retentionPeriod sibling fields reflect the requested
unit. Each retentionPeriod is omitted per entry when its source
value is unset.
Default: omitted (retentionPeriod sibling fields absent).
DurationUnit specifies the time unit a Duration value is expressed in.
Used by APIs that report or accept a derived integer duration alongside
its unit, including schedule frequencies and retention durations on
protection-policy and protection-run responses (and by the matching
'durationUnit' query parameter that selects the unit those responses
should be expressed in).
