private static ArrayList<HStoreFile> flattenLists(ArrayList<HStoreFile>... sfls) {
    ArrayList<HStoreFile> result = new ArrayList<>();
    for (ArrayList<HStoreFile> sfl : sfls) {
      result.addAll(sfl);
    }
    return result;
  }
Verifies scenario for finding a split point.
@param splitPointAfter    Stripe to expect the split point at/after.
@param shouldSplitStripe  If true, the split point is expected in the middle of the above
                          stripe; if false, should be at the end.
@param splitRatioToVerify Maximum split imbalance ratio.
@param sizes              Stripe sizes.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestStripeStoreFileManager.java