Unwanted unknownFields appear after upgrading from 0.7.2

[Paul B.]

Let's say I have the following message:

```

syntax = "proto3";

package com.foo.mynotifications;

message MyNotification {
    string user_id = 1;
    string message = 2;
    string message_body = 5;
}

```

In plugins.sbt I have:

addSbtPlugin("com.lightbend.akka.grpc" % "sbt-akka-grpc" % "0.7.2")

The generated case class has the following signature:

final case class MyNotification(userId: String, message: String)

If I upgrade sbt-akka-grpc to 0.8.0or any version above that, the generated case class will receive a new field and will have the following signature:

final case class MyNotification(userId: String, message: String, unknownFields: UnknownFieldSet)

Is there a way to upgrade without getting the unknownFields: UnknownFieldSet field added to all the classes generated from my messages? 

Having to cope with the new field would mean I'll have to update quite a big amount of code in my services.

[Paul B.]

Please ignore

    string message_body = 5;

from the message in my initial post.