static Optional<byte[]> getSplitPoint(Collection<HStoreFile> storefiles,
    CellComparator comparator) throws IOException {
    Optional<HStoreFile> largestFile = StoreUtils.getLargestFile(storefiles);
    return largestFile.isPresent()
      ? StoreUtils.getFileSplitPoint(largestFile.get(), comparator)
      : Optional.empty();
  }
Gets the mid point of the largest file passed in as split point.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreUtils.java