Deserialization error when execute GET a non-existing alias

[bachden]

execute simple test case as follow:

import org.junit.jupiter.api.Test;

public class TestEsAliasCommands extends AbstractEsCallerTest {

    @Test
    void testGetNotExistingAlias() {
        try {
            getEsClient().indices().getAlias(g -> g.name("not-existing-alias")).toCompletableFuture().get();
        } catch (Throwable e) {
            e.printStackTrace();
        }
    }
}

where getEsClient() return an ElasticsearchAsyncClient instance. error as follow:

co.elastic.clients.json.UnexpectedJsonEventException: Unexpected JSON event 'VALUE_STRING' instead of '[START_OBJECT, KEY_NAME]'
	at co.elastic.clients.json.JsonpUtils.ensureAccepts(JsonpUtils.java:68)
	at co.elastic.clients.json.JsonpDeserializer.deserialize(JsonpDeserializer.java:74)
	at co.elastic.clients.json.ObjectBuilderDeserializer.deserialize(ObjectBuilderDeserializer.java:79)
	at co.elastic.clients.json.DelegatingDeserializer$SameType.deserialize(DelegatingDeserializer.java:43)
	at co.elastic.clients.json.ObjectDeserializer$FieldObjectDeserializer.deserialize(ObjectDeserializer.java:72)
	at co.elastic.clients.json.ObjectDeserializer.deserialize(ObjectDeserializer.java:176)
	at co.elastic.clients.json.ObjectDeserializer.deserialize(ObjectDeserializer.java:137)
	at co.elastic.clients.json.JsonpDeserializer.deserialize(JsonpDeserializer.java:75)
	at co.elastic.clients.json.ObjectBuilderDeserializer.deserialize(ObjectBuilderDeserializer.java:79)
	at co.elastic.clients.json.DelegatingDeserializer$SameType.deserialize(DelegatingDeserializer.java:43)
	at co.elastic.clients.transport.rest_client.RestClientTransport.getHighLevelResponse(RestClientTransport.java:276)
	at co.elastic.clients.transport.rest_client.RestClientTransport.access$200(RestClientTransport.java:60)
	at co.elastic.clients.transport.rest_client.RestClientTransport$1.onSuccess(RestClientTransport.java:165)
	at org.elasticsearch.client.RestClient$FailureTrackingResponseListener.onSuccess(RestClient.java:649)
	at org.elasticsearch.client.RestClient$1.completed(RestClient.java:383)
	at org.elasticsearch.client.RestClient$1.completed(RestClient.java:377)
	at org.apache.http.concurrent.BasicFuture.completed(BasicFuture.java:122)
	at org.apache.http.impl.nio.client.DefaultClientExchangeHandlerImpl.responseCompleted(DefaultClientExchangeHandlerImpl.java:181)
	at org.apache.http.nio.protocol.HttpAsyncRequestExecutor.processResponse(HttpAsyncRequestExecutor.java:448)
	at org.apache.http.nio.protocol.HttpAsyncRequestExecutor.inputReady(HttpAsyncRequestExecutor.java:338)
	at org.apache.http.impl.nio.DefaultNHttpClientConnection.consumeInput(DefaultNHttpClientConnection.java:265)
	at org.apache.http.impl.nio.client.InternalIODispatch.onInputReady(InternalIODispatch.java:81)
	at org.apache.http.impl.nio.client.InternalIODispatch.onInputReady(InternalIODispatch.java:39)
	at org.apache.http.impl.nio.reactor.AbstractIODispatch.inputReady(AbstractIODispatch.java:114)
	at org.apache.http.impl.nio.reactor.BaseIOReactor.readable(BaseIOReactor.java:162)
	at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvent(AbstractIOReactor.java:337)
	at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvents(AbstractIOReactor.java:315)
	at org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:276)
	at org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:104)
	at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:591)
	at java.base/java.lang.Thread.run(Thread.java:833)

environment:

• server: docker image docker.elastic.co/elasticsearch/elasticsearch:7.16.2
• client: version 7.16.2

[swallez]

Thanks for the report. This was caused by Elasticsearch responding with an error in "compact format" where the error property is a simple string instead of an object. Fixed by allowing both forms in ErrorCause deserializer.

[synox]

I am facing the same issue with client 7.16.2 and 7.17.1. Is this going to be backported?
cc: @fabriziofortino