private static long generateRegionId() {
    return Instant.ofEpochMilli(EnvironmentEdgeManager.currentTime())
      .minus(Period.ofDays(DEFAULT_MERGE_MIN_REGION_AGE_DAYS + 1)).toEpochMilli();
  }
Create a list of {@link RegionInfo}s that represent a region chain of the specified length.
hbase-server/src/test/java/org/apache/hadoop/hbase/master/normalizer/TestSimpleRegionNormalizer.java