private Map<ShapeId, ShapeId> getRenamedShapesConnectedToService(Config config, Model model) {
        Walker shapeWalker = new Walker(NeighborProviderIndex.of(model).getProvider());
        ServiceShape service = model.expectShape(config.getService(), ServiceShape.class);
        return shapeWalker.walkShapes(service)
                .stream()
                .filter(FunctionalUtils.not(Prelude::isPreludeShape))
                .map(shape -> Pair.of(shape.getId(), updateNamespace(shape.getId(), config.getNamespace())))
                .map(pair -> applyServiceRenames(pair.getLeft(), pair.getRight(), service))
                .collect(Collectors.toMap(Pair::getLeft, Pair::getRight));
    }
Gets the set of tags that are retained in the model.

@return Returns the tags to retain.
smithy-build/src/main/java/software/amazon/smithy/build/transforms/FlattenNamespaces.java