@Override
        @SuppressWarnings("unchecked")
        public Node serialize(Optional value, Set<Object> serializedObjects, NodeMapper mapper) {
            return (Node) value.map(v -> mapper.serialize(v, serializedObjects)).orElse(Node.nullNode());
        }
The default implementations use to convert Objects to Node values in {@link NodeMapper}.
smithy-model/src/main/java/software/amazon/smithy/model/node/DefaultNodeSerializers.java