OptionalDefaultLifetime, in days, for log rows that carry no retention of their own.
Omitted means those rows are kept indefinitely. That is the deliberate default: a NULL retention is what the schema calls "indefinite", and a purge job that silently supplied a number would delete history nobody agreed to lose.
OptionalMaxCeiling on rows deleted per run. Defaults to DEFAULT_MAX_DELETES_PER_RUN.
Optional configuration (stored in
ScheduledJob.Configuration). Every field is optional.