@Override
    protected void check(IntEnumShape shape, NumberNode node, Context context, Emitter emitter) {
        Collection<Integer> values = shape.getEnumValues().values();
        if (!values.contains(node.getValue().intValue())) {
            emitter.accept(node,
                    String.format(
                            "Integer value provided for `%s` must be one of the following values: %s, but found %s",
                            shape.getId(),
                            ValidationUtils.tickedList(values),
                            node.getValue()));
        }
    }
Validates NumberNodes against intEnum shapes' allowed enum values.
smithy-model/src/main/java/software/amazon/smithy/model/validation/node/IntEnumPlugin.java