private ShapeId updateNamespace(ShapeId shapeId, String namespace) {
        if (shapeId.getMember().isPresent()) {
            return ShapeId.fromParts(namespace, shapeId.getName(), shapeId.getMember().get());
        }
        return ShapeId.fromParts(namespace, shapeId.getName());
    }
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