private boolean isTargetingStructureOrUnion(Model model, MemberShape member) {
        Shape target = model.expectShape(member.getTarget());
        return target.isStructureShape() || target.isUnionShape();
    }
Whether clientOptional is required for all members marked as required or default.

@return Returns true if required.
smithy-linters/src/main/java/software/amazon/smithy/linters/MissingClientOptionalTrait.java