calling hotThreads fails because of text/plain response format vs json

[dadoonet]

Java API client version

8.15.0

Java version

21.0

Elasticsearch Version

8.15.0

Problem description

Reported at https://discuss.elastic.co/t/365144 and reproduced loally.

With the 8.15.0 client, run:

HotThreadsResponse hotThreadsResponse = client.nodes().hotThreads();

This gives:

co.elastic.clients.transport.TransportException: node: https://localhost:63624/, status: 200, [es/nodes.hot_threads] Expecting JSON data but response content-type is: text/plain; charset=UTF-8

	at co.elastic.clients.transport.ElasticsearchTransportBase.checkJsonContentType(ElasticsearchTransportBase.java:471)
	at co.elastic.clients.transport.ElasticsearchTransportBase.decodeTransportResponse(ElasticsearchTransportBase.java:394)
	at co.elastic.clients.transport.ElasticsearchTransportBase.getApiResponse(ElasticsearchTransportBase.java:363)
	at co.elastic.clients.transport.ElasticsearchTransportBase.performRequest(ElasticsearchTransportBase.java:147)
	at co.elastic.clients.elasticsearch.nodes.ElasticsearchNodesClient.hotThreads(ElasticsearchNodesClient.java:199)
	at fr.pilato.test.elasticsearch.hlclient.EsClientIT.callHotThreads(EsClientIT.java:956)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)