@Override
    public List<ValidationEvent> evaluate(Differences differences) {
        List<ValidationEvent> events = newRequiredMembers(differences)
                .map(this::emit)
                .collect(Collectors.toList());

        return events;
    }
Validates that no members are newly created with the required trait
(but no default trait) in existing structures.
smithy-diff/src/main/java/software/amazon/smithy/diff/evaluators/AddedRequiredMember.java