@Override
    public List<ValidationEvent> evaluate(Differences differences) {
        return differences.changedShapes(ResourceShape.class)
                .filter(diff -> !diff.getOldShape().getIdentifiers().equals(diff.getNewShape().getIdentifiers()))
                .map(diff -> error(diff.getNewShape(),
                        String.format(
                                "Identifiers of resource `%s` changed from %s to %s.",
                                diff.getShapeId(),
                                diff.getOldShape().getIdentifiers(),
                                diff.getNewShape().getIdentifiers())))
                .collect(Collectors.toList());
    }
Creates an ERROR event when the identifiers of a resource changes.
smithy-diff/src/main/java/software/amazon/smithy/diff/evaluators/ChangedResourceIdentifiers.java