@Override
        public Void structureShape(StructureShape shape) {
            if (shape.hasTrait(ErrorTrait.ID)) {
                LOGGER.finest(() -> "Generating error " + shape.getId());
                directedCodegen.generateError(new GenerateErrorDirective<>(context, serviceShape, shape));
            } else {
                LOGGER.finest(() -> "Generating structure " + shape.getId());
                directedCodegen.generateStructure(new GenerateStructureDirective<>(context, serviceShape, shape));
            }
            return null;
        }
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