private void performModelTransforms() {
        LOGGER.fine(() -> "Performing model transformations for " + directedCodegen.getClass().getName());
        ModelTransformer transformer = ModelTransformer.create();
        for (BiFunction<Model, ModelTransformer, Model> transform : transforms) {
            model = transform.apply(model, transformer);
        }
    }
Finalizes the Runner and performs directed code generation.

@throws IllegalStateException if a required value has not been provided.
smithy-codegen-core/src/main/java/software/amazon/smithy/codegen/core/directed/CodegenDirector.java