@Override
    public int getSerializedSize(boolean withTags) {
      int len = ((ExtendedCell) this.cell).getSerializedSize(false);
      if (withTags && this.tags != null) {
        len += KeyValue.TAGS_LENGTH_SIZE + this.tags.length;
      }
      return len;
    }
@param cell The original ByteBufferExtendedCell which it rewrites
@param tags the tags bytes. The array suppose to contain the tags bytes alone.
hbase-common/src/main/java/org/apache/hadoop/hbase/PrivateCellUtil.java