MessagePack Java 0.6.X optional fields

You can add a new field to maintain availability. In the new field  @Optional notes.

@Message
public static class MyMessage {
    public String name;
    public double version;
  
    // new field
    @Optional
    public int flag = 0;
}

If you try to deserialize the old version of the data, optional fields will be ignored.

 

https://www.cwiki.us/display/Serialization/QuickStart+For+MessagePack+Java+0.6.X