Null is your friend, not a mistake

Null is a concept--there is no data here. We need the concept and code needs to be able to act on it. If you rewrite the code to avoid all possible nulls you have done nothing to ensure that everything is operating on sane data, you have simply removed the easy mechanism that flagged cases the developer failed to handle.

In most cases you're better off going boom than operating on wrong data and getting rid of nulls shifts the balance towards the latter.

Because

    int id = args.getOptional().orElseThrow(() -> new Error("id expected"));