private boolean memberTargetHasTrait(Model model, MemberShape member, ShapeId trait) {
        return model.getShape(member.getTarget())
                .flatMap(target -> target.findTrait(trait))
                .isPresent();
    }
Validates traits that can only be applied to a single structure member.
smithy-model/src/main/java/software/amazon/smithy/model/validation/validators/ExclusiveStructureMemberTraitValidator.java