private static List<MessageClassGenerator> createMessageClassGenerators(String packageName,
                                                                            List<String> types) {
        if (types == null) return Collections.emptyList();
        List<MessageClassGenerator> generators = new ArrayList<>();
        for (String type : types) {
            switch (type) {
                case "MessageDataGenerator":
                    generators.add(new MessageDataGenerator(packageName));
                    break;
                case "JsonConverterGenerator":
                    generators.add(new JsonConverterGenerator(packageName));
                    break;
                default:
                    throw new RuntimeException("Unknown message class generator type '" + type + "'");
            }
        }
        return generators;
    }
The Jackson serializer we use for JSON objects.
generator/src/main/java/org/apache/kafka/message/MessageGenerator.java