@Override
  public int getSerializedSize() {
    return this.length;
  }
Write out a KeyValue in the manner in which we used to when KeyValue was a Writable.
@param kv  the KeyValue on which write is being requested
@param out OutputStream to write keyValue to
@return Length written on stream
@throws IOException if any IO error happen
@see #create(DataInput) for the inverse function
hbase-common/src/main/java/org/apache/hadoop/hbase/KeyValue.java