@Override
    public List<ValidationEvent> validate(Model model) {
        TopDownIndex topDownIndex = TopDownIndex.of(model);
        return model.shapes(ServiceShape.class)
                .flatMap(shape -> validateService(topDownIndex, shape).stream())
                .collect(Collectors.toList());
    }
Validates that a resource is only bound to once in an entire
service closure.
smithy-model/src/main/java/software/amazon/smithy/model/validation/validators/SingleResourceBindingValidator.java