Check if sniffer was able to determine the version before testing if it's a 2.x

[marko-bekhta]

Hey 👋🏻 🙂,

I've run into this:

(es_rest_client_sniffer[T#1]) ERROR Sniffer:140 - error while sniffing nodes
java.lang.NullPointerException: Cannot invoke "String.startsWith(String)" because "version" is null
	at co.elastic.clients.transport.rest5_client.low_level.sniffer.ElasticsearchNodesSniffer.readNode(ElasticsearchNodesSniffer.java:255)
	at co.elastic.clients.transport.rest5_client.low_level.sniffer.ElasticsearchNodesSniffer.readHosts(ElasticsearchNodesSniffer.java:123)
	at co.elastic.clients.transport.rest5_client.low_level.sniffer.ElasticsearchNodesSniffer.sniff(ElasticsearchNodesSniffer.java:107)
	at co.elastic.clients.transport.rest5_client.low_level.sniffer.Sniffer.sniff(Sniffer.java:207)
	at co.elastic.clients.transport.rest5_client.low_level.sniffer.Sniffer$Task.run(Sniffer.java:138)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:545)
	at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:328)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
	at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:309)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1090)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:614)
	at java.base/java.lang.Thread.run(Thread.java:1474)

while I was looking into Hibernate Search CI failure (that particular test uses different Elasticsearch clients and "backends" including the one which supposedly won't return the version in the nodes response to sniffer...). So I thought I'd open a PR and let you decide if you want to include the fix 😃.
Alternatively, maybe let's just set String version = ""; ?

[cla-checker-service]

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[l-trotta]

Hello, thanks for the PR! I'm very curious: how did you manage to get a node info response without the version field? It should be always present in the response (as per the response builder in the server code), and in fact the rest 5 client sniffer code has been copied and updated from the original sniffer in the elasticsearch server code.

[marko-bekhta]

hi 🙂 👋🏻

how did you manage to get a node info response without the version field?

ahh, so that particular request to get the version is mocked and in one of the test scenarios the version value is removed from it on purpose... That scenario was suppose to imitate the call to the early versions of the opensearch serverless distribution, which at those times was either not returning the version at all or when it was returning something, it wasn't usable 🫣. (I don't have access to that service anymore so can't confirm if they changed it or not)

I debugged the sniffer/client from the server distribution (apache 4 based one) and it does not have this null exception as it ends up parsing the null as "null" (string).
It's probably the change to Jakarta Json from Jackson that introduced that "difference in behavior" between these two clients 🤔