@Override
  public void init(ByteArrayRef bytes, int start, int length) {
    data.set(bytes.getData(), start);
  }
Initializes LazyBinaryTimestamp object
@param bytes
@param start
@param length
   If length is 4, no decimal bytes follow, otherwise read following bytes
   as VInt and reverse its value
serde/src/java/org/apache/hadoop/hive/serde2/lazybinary/LazyBinaryTimestamp.java