@SuppressWarnings({ "rawtypes", "unchecked" })
private ProtobufHttpMessageConverter newCustomProtobufMessageConverter() throws Exception {
    Constructor[] constructors = ProtobufHttpMessageConverter.class.getDeclaredConstructors();
    Constructor requiredConstructor = null;
    for (Constructor constructor : constructors) {
        if (constructor.getParameterTypes().length == 2) {
            constructor.setAccessible(true);
            requiredConstructor = constructor;
            break;
        }
    }

    Class[] classes = ProtobufHttpMessageConverter.class.getDeclaredClasses();
    Class requiredClass = null;
    for (Class clazz : classes) {
        if (clazz.getSimpleName().equals("ProtobufJavaUtilSupport")) {
            requiredClass = clazz;
            break;
        }
    }

    Constructor pbUtilSupportConstructor = requiredClass.getConstructor(Parser.class, Printer.class);
    pbUtilSupportConstructor.setAccessible(true);

    Parser parser = JsonFormat.parser().ignoringUnknownFields();
    Printer printer = JsonFormat.printer().includingDefaultValueFields().preservingProtoFieldNames()
            .omittingInsignificantWhitespace();
    Object support = pbUtilSupportConstructor.newInstance(parser, printer);
    return (ProtobufHttpMessageConverter) requiredConstructor.newInstance(support, null);
}
 

public static List<DynamicMessage> parseToMessages(TypeRegistry registry, Descriptor descriptor,
        List<String> jsonTexts) {
    Parser parser = JsonFormat.parser().usingTypeRegistry(registry);
    List<DynamicMessage> messages = new ArrayList<>();
    try {
        for (String jsonText : jsonTexts) {
            DynamicMessage.Builder messageBuilder = DynamicMessage.newBuilder(descriptor);
            parser.merge(jsonText, messageBuilder);
            messages.add(messageBuilder.build());
        }
        return messages;
    } catch (InvalidProtocolBufferException e) {
        throw new IllegalArgumentException("Unable to parse json text", e);
    }
}
 

public static List<DynamicMessage> parseToMessages(TypeRegistry registry, Descriptor descriptor,
        List<String> jsonTexts) {
    Parser parser = JsonFormat.parser().usingTypeRegistry(registry);
    List<DynamicMessage> messages = new ArrayList<>();
    try {
        for (String jsonText : jsonTexts) {
            DynamicMessage.Builder messageBuilder = DynamicMessage.newBuilder(descriptor);
            parser.merge(jsonText, messageBuilder);
            messages.add(messageBuilder.build());
        }
        return messages;
    } catch (InvalidProtocolBufferException e) {
        throw new IllegalArgumentException("Unable to parse json text", e);
    }
}
 

/**
 * Create a {@code Marshaller} for json protos of the same type as {@code defaultInstance}.
 *
 * <p>This is an unstable API and has not been optimized yet for performance.
 */
public static <T extends Message> Marshaller<T> jsonMarshaller(final T defaultInstance) {
  final Parser parser = JsonFormat.parser();
  final Printer printer = JsonFormat.printer();
  return jsonMarshaller(defaultInstance, parser, printer);
}
 

/**
 * Create a {@code Marshaller} for json protos of the same type as {@code defaultInstance}.
 *
 * <p>This is an unstable API and has not been optimized yet for performance.
 */
public static <T extends Message> Marshaller<T> jsonMarshaller(final T defaultInstance) {
  final Parser parser = JsonFormat.parser();
  final Printer printer = JsonFormat.printer();
  return jsonMarshaller(defaultInstance, parser, printer);
}