code: private static long getBlockSize(LocatedBlocks lbs) throws IOException {
      List<LocatedBlock> locatedBlocks = lbs.getLocatedBlocks();
      long bs = -1;
      for (LocatedBlock lb: locatedBlocks) {
        if (lb.getBlockSize() > bs) {
          bs = lb.getBlockSize();
        }
      }
      return bs;
    }
docs: Obtain block size given 3 or more blocks