This change here would break backwards compatibility, which is something we want to avoid between minor versions.
Think about a rolling upgrade, a node running an older version would receive a different binary object which it doesn't know how to decode, same the other way around, if a newer node receives the old format.
The way we solve this is adding an `if` that checks the version of the `in` and `out` in both `readFrom` and `writeTo`. Have a look at the [`PutWarmerRequest`](https://github.com/elasticsearch/elasticsearch/blob/master/src/main/java/org/elasticsearch/action/admin/indices/warmer/put/PutWarmerRequest.java#L123) for instance. Can you do the same here?