[CI] [_doc] can't start with '_' bwc tests failure

[martijnvg]

There are FullClusterRestartIT failures that failed with mapping type name [_doc] can't start with '_' error.

Example reproduction: ./gradlew :qa:full-cluster-restart:v6.0.0#oldClusterTestRunner -Dtests.seed=82454A4C76256306 -Dtests.class=org.elasticsearch.upgrades.FullClusterRestartIT -Dtests.method="testNewReplicasWork" -Dtests.security.manager=true -Dtests.locale=es-HN -Dtests.timezone=America/Indiana/Vincennes -Dtests.distribution=zip -Dcompiler.java=11 -Druntime.java=8

Example failure:

Caused by: org.elasticsearch.client.ResponseException: method [PUT], host [http://[::1]:43277], URI [/testnewreplicaswork], status line [HTTP/1.1 400 Bad Request]
07:49:25    > {"error":{"root_cause":[{"type":"invalid_type_name_exception","reason":"mapping type name [_doc] can't start with '_'"}],"type":"invalid_type_name_exception","reason":"mapping type name [_doc] can't start with '_'"},"status":400}
07:49:25    > 	at org.elasticsearch.client.RestClient$1.completed(RestClient.java:309)
07:49:25    > 	at org.elasticsearch.client.RestClient$1.completed(RestClient.java:294)
07:49:25    > 	at org.apache.http.concurrent.BasicFuture.completed(BasicFuture.java:119)
07:49:25    > 	at org.apache.http.impl.nio.client.DefaultClientExchangeHandlerImpl.responseCompleted(DefaultClientExchangeHandlerImpl.java:177)
07:49:25    > 	at org.apache.http.nio.protocol.HttpAsyncRequestExecutor.processResponse(HttpAsyncRequestExecutor.java:436)
07:49:25    > 	at org.apache.http.nio.protocol.HttpAsyncRequestExecutor.inputReady(HttpAsyncRequestExecutor.java:326)
07:49:25    > 	at org.apache.http.impl.nio.DefaultNHttpClientConnection.consumeInput(DefaultNHttpClientConnection.java:265)
07:49:25    > 	at org.apache.http.impl.nio.client.InternalIODispatch.onInputReady(InternalIODispatch.java:81)
07:49:25    > 	at org.apache.http.impl.nio.client.InternalIODispatch.onInputReady(InternalIODispatch.java:39)
07:49:25    > 	at org.apache.http.impl.nio.reactor.AbstractIODispatch.inputReady(AbstractIODispatch.java:114)
07:49:25    > 	at org.apache.http.impl.nio.reactor.BaseIOReactor.readable(BaseIOReactor.java:162)
07:49:25    > 	at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvent(AbstractIOReactor.java:337)
07:49:25    > 	at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvents(AbstractIOReactor.java:315)
07:49:25    > 	at org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:276)
07:49:25    > 	at org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:104)
07:49:25    > 	at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:588)
07:49:25    > 	... 1 more

Other build failures:

• https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+master+bwc-tests/195/console
• https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+master+default-distro-bwc-tests/167/console

Related PR #35930

[elasticmachine]

Pinging @elastic/es-search

[martijnvg]

Early 6.x ES versions don't allow _doc as type name, so looks like certain FullClusterRestartIT tests need to be skipped when testing against these early 6.x versions.

[astefan]

https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+master+default-distro-bwc-tests/170/console

[jtibshirani]

I merged #36511 to address the test failures and will keep an eye on the BWC builds.

[martijnvg]

Thanks @jtibshirani!