I have a simple problem. I have a large class:

public class Base {
    public Field1Data field1;
    public Field2Data field2;
    public Field3Data field3;
    // many more fields later...
    public Field1234Data field1234;
}

It has a very large number of fields, with a very large number of types.

Then I have an extension:

public class UpgradedBase extends Base {
    public String metadata;
}

I want a concise way to write the following method:

public static UpgradedBase upgrade(Base baseInstance, String metadata){
   /// What I don't know how to write.
}

I have Lombok, but that’s about it as far as code-gen tools go.
How can I write the upgrade method above? I’d prefer a concise method.