bucket
    .toBuilder()
    .setLifecycleRules(
        ImmutableList.of(
            new LifecycleRule(
                LifecycleRule.LifecycleAction.newDeleteAction(),
                LifecycleRule.LifecycleCondition.newBuilder()
                    .setDaysSinceNoncurrentTime(30)
                    .setNoncurrentTimeBefore(/* Date object */)
                    .build())))
    .build()
    .update();