private final ArrayList<HStoreFile> getStripeCopy(int index) {
      List<HStoreFile> stripeCopy = this.stripeFiles.get(index);
      ArrayList<HStoreFile> result = null;
      if (stripeCopy instanceof ImmutableList<?>) {
        result = new ArrayList<>(stripeCopy);
        this.stripeFiles.set(index, result);
      } else {
        result = (ArrayList<HStoreFile>) stripeCopy;
      }
      return result;
    }
@param index Index of the stripe we need.
@return A lazy stripe copy from current stripes.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StripeStoreFileManager.java