private Optional<Node> createOptionalIdList(Collection<ShapeId> list) {
            if (list.isEmpty()) {
                return Optional.empty();
            }

            Node result = list.stream()
                    .sorted()
                    .map(this::serializeReference)
                    .collect(ArrayNode.collect());
            return Optional.of(result);
        }
Sets the IDL version to serialize. Defaults to 2.0.

<p>Version "1.0" serialization cannot be used with {@link #includePrelude}.

@param version IDL version to set. Can be "1", "1.0", "2", or "2.0".
               "1" and "2" are normalized to "1.0" and "2.0".
@return Returns the builder.
smithy-model/src/main/java/software/amazon/smithy/model/shapes/ModelSerializer.java