fn group_region_by_topic(
region_id: RegionId,
region_options: &RegionWalOptions,
topic_regions: &mut HashMap<String, Vec<RegionId>>,
)fn group_region_by_topic(
region_id: RegionId,
region_options: &RegionWalOptions,
topic_regions: &mut HashMap<String, Vec<RegionId>>,
)