@Override
  public long skip(final long len) throws IOException {
    long skipped = in.skip(Math.min(len, limit - pos));
    pos += skipped;
    return skipped;
  }
This class is only used by WAL ValueCompressor for decompression.
<p>
<strong>WARNING: </strong>The implementation is very tricky and does not follow typical
InputStream pattern, so do not use it in any other places.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALDecompressionBoundedDelegatingInputStream.java