Fix parsing of UserUpdatedEvents

[pvancoeverden]

Changes

When I subscribed to UserUpdateEvents, all events are of the type: EventStreamSubscribeEventsResponseContent._UnknownValue, without readable data. This commit fixes this. Added a EventsSubscribeSseTest that shows the original problem.

References

Example code to reproduce the bug:

	private void connect()
	{
		final SubscribeEventsRequestParameters.Builder settings = SubscribeEventsRequestParameters.builder()
			.eventType(EventStreamSubscribeEventsEventTypeEnum.USER_UPDATED);

		final Optional<String> offset = syncService.getOffset(EVENT_TYPE_KEY);
		if (offset.isPresent())
		{
			settings.from(offset.get());
		}
		else
		{
			settings.fromTimestamp(startOfDay());
		}

		log.info("Subscribing to Auth0 user.updated event stream (resuming from {})", offset.map(o -> "offset " + o).orElse("start of day"));
		final Iterable<EventStreamSubscribeEventsResponseContent> stream = apiProvider.getManagementApi().events().subscribe(settings.build());
		try
		{
			for (EventStreamSubscribeEventsResponseContent event : stream)
			{
				try
				{
					handleEvent(event);
				}
				catch (Exception e)
				{
					// A single malformed event must not tear down the whole stream.
					log.error("Failed to handle Auth0 event", e);
				}
			}
		}
		finally
		{
			closeQuietly(stream);
		}
	}

	private void handleEvent(EventStreamSubscribeEventsResponseContent event)
	{
		if (event.getUserUpdated().isPresent())
		{
			handleUserUpdated(event.getUserUpdated().get());
			return;
		}
		if (event.getOffsetOnly().isPresent())
		{
			handleOffsetOnly(event.getOffsetOnly().get());
			return;
		}
		if (event._isUnknown())
		{
			log.warn("Received unknown Auth0 event type, ignoring: {}", event);
		}
	}

All events will print Received unknown Auth0 event type, ignoring: EventStreamSubscribeEventsResponseContent{type: null, value: null}

This is because the response is not parsed correctly: the value of all events are of type '_Unkown instead of the correct value

I've added the EventsSubscribeSseTest wich mimics the example code.

Please include relevant links supporting this change:

• Event Streams SSE subscription always deserializes events to _UnknownValue #897
• https://auth0.com/docs/customize/events/consume-events-with-events-api

Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. If this library has unit and/or integration testing, tests should be added for new functionality and existing tests should complete without errors.

• This change adds test coverage
• This change has been tested on the latest version of the platform/language or why not

Tested with java 21 in our own project, and build the unit-tests with java 17 because spotless did not work with my later java versions. (com.sun libs missing)

Checklist

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct
• All existing and new tests complete without errors

[pvancoeverden]

Fixes #897

[pvancoeverden]

I realize now that some code is generated with Fern. But this project has no information how it is generated. I think it is better to fiddle with the api-spec and/or fern configuration to fix this bug.