public void makeIdempotencyTokensClientOptional() {
        transforms.add((model, transformer) -> {
            LOGGER.finest("Making `@idempotencyToken` fields `@clientOptional`");
            return transformer.makeIdempotencyTokensClientOptional(model);
        });
    }
Makes {@code idempotencyToken} fields {@code clientOptional}.

@see ModelTransformer#makeIdempotencyTokensClientOptional(Model)
smithy-codegen-core/src/main/java/software/amazon/smithy/codegen/core/directed/CodegenDirector.java