RestHighLevelClient throws exception parsing RareTerms aggregation results

[ajeydudhe]

Elasticsearch version (bin/elasticsearch --version): 7.9.2

Plugins installed: []

JVM version (java -version):
java version "1.8.0_251"
Java(TM) SE Runtime Environment (build 1.8.0_251-b08)
Java HotSpot(TM) 64-Bit Server VM (build 25.251-b08, mixed mode)

OS version (uname -a if on a Unix-like system):
Darwin Ajeys-MacBook-Pro.local 19.6.0 Darwin Kernel Version 19.6.0: Thu Jun 18 20:49:00 PDT 2020; root:xnu-6153.141.1~1/RELEASE_X86_64 x86_64

Description of the problem including expected versus actual behavior:
Performing the RareTerms aggregation using the RestHighLevelClient. The request seems to execute on server side and results are also returned. From the exception stack it looks like the client is not able to parse the RareTerms aggregation result. Also, the AggregationBuilders does not have the helper method for RareTerms aggregation so creating the instance directly. Note that other searches or aggregations work as expected.

Steps to reproduce:
The search request is created as follllows

final SearchSourceBuilder searchBuilder = new SearchSourceBuilder();
searchBuilder.aggregation(new RareTermsAggregationBuilder("rare_terms_aggs").field("some.field").maxDocCount(5));

Provide logs (if relevant):

java.io.IOException: Unable to parse response body for Response{requestLine=POST /businesses/_search?typed_keys=true&max_concurrent_shard_requests=5&ignore_unavailable=false&expand_wildcards=open&allow_no_indices=true&ignore_throttled=true&search_type=query_then_fetch&batched_reduce_size=512&ccs_minimize_roundtrips=true HTTP/1.1, host=http://localhost:9200, response=HTTP/1.1 200 OK}
        at org.elasticsearch.client.RestHighLevelClient.internalPerformRequest(RestHighLevelClient.java:1632)
        at org.elasticsearch.client.RestHighLevelClient.performRequest(RestHighLevelClient.java:1583)
        at org.elasticsearch.client.RestHighLevelClient.performRequestAndParseEntity(RestHighLevelClient.java:1553)
        at org.elasticsearch.client.RestHighLevelClient.search(RestHighLevelClient.java:1069)
        at my.code.search.ElasticsearchClient.invoke(ElasticsearchClient.java:105)
        at my.code.search.ElasticsearchClient.search(ElasticsearchClient.java:52)
        at my.code.search.SearchHandler.getBusinessCountByCity(SearchHandler.java:253)
        at my.code.search.SearchIT.testBusinessCountByCity_noRecordsForCitiesWithLessThan5Businesses(SearchIT.java:319)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:124)
        at org.testng.internal.Invoker.invokeMethod(Invoker.java:583)
        at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:719)
        at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:989)
        at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
        at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
        at org.testng.TestRunner.privateRun(TestRunner.java:648)
        at org.testng.TestRunner.run(TestRunner.java:505)
        at org.testng.SuiteRunner.runTest(SuiteRunner.java:455)
        at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450)
        at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415)
        at org.testng.SuiteRunner.run(SuiteRunner.java:364)
        at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
        at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84)
        at org.testng.TestNG.runSuitesSequentially(TestNG.java:1208)
        at org.testng.TestNG.runSuitesLocally(TestNG.java:1137)
        at org.testng.TestNG.runSuites(TestNG.java:1049)
        at org.testng.TestNG.run(TestNG.java:1017)
        at org.apache.maven.surefire.testng.TestNGExecutor.run(TestNGExecutor.java:135)
        at org.apache.maven.surefire.testng.TestNGDirectoryTestSuite.executeSingleClass(TestNGDirectoryTestSuite.java:112)
        at org.apache.maven.surefire.testng.TestNGDirectoryTestSuite.execute(TestNGDirectoryTestSuite.java:99)
        at org.apache.maven.surefire.testng.TestNGProvider.invoke(TestNGProvider.java:146)
        at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:384)
        at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:345)
        at org.apache.maven.surefire.booter.ForkedBooter.execute(ForkedBooter.java:126)
        at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:418)
Caused by: org.elasticsearch.common.xcontent.NamedObjectNotFoundException: [1:208] unknown field [srareterms]
        at org.elasticsearch.common.xcontent.NamedXContentRegistry.parseNamedObject(NamedXContentRegistry.java:132)
        at org.elasticsearch.common.xcontent.support.AbstractXContentParser.namedObject(AbstractXContentParser.java:385)
        at org.elasticsearch.common.xcontent.XContentParserUtils.parseTypedKeysObject(XContentParserUtils.java:153)
        at org.elasticsearch.search.aggregations.Aggregations.fromXContent(Aggregations.java:142)
        at org.elasticsearch.action.search.SearchResponse.innerFromXContent(SearchResponse.java:306)
        at org.elasticsearch.action.search.SearchResponse.fromXContent(SearchResponse.java:265)
        at org.elasticsearch.client.RestHighLevelClient.parseEntity(RestHighLevelClient.java:1892)
        at org.elasticsearch.client.RestHighLevelClient.lambda$performRequestAndParseEntity$8(RestHighLevelClient.java:1554)
        at org.elasticsearch.client.RestHighLevelClient.internalPerformRequest(RestHighLevelClient.java:1630)
        ... 37 common frames omitted

[elasticmachine]

Pinging @elastic/es-core-features (:Core/Features/Java High Level REST Client)

[swallez]

Should be fixed by PR #64454 and its backports to 7.x and 7.10