public Model makeIdempotencyTokensClientOptional(Model model) {
        return MakeIdempotencyTokenClientOptional.transform(model);
    }
Makes any {@code @idempotencyToken} fields {@code @clientOptional} so that missing tokens can be injected.

<p>Idempotency tokens that are required should fail validation, but shouldn't be required to create a type,
allowing for a default value to be injected when missing.

@param model Model to transform.
@return Returns the transformed model.
smithy-model/src/main/java/software/amazon/smithy/model/transform/ModelTransformer.java