**Build scan:**
https://gradle-enterprise.elastic.co/s/3iejlt6s5z2gq/tests/:x-pack:plugin:esql:qa:server:single-node:javaRestTest/org.elasticsearch.xpack.esql.qa.single_node.RestEsqlIT/testWarningHeadersOnFailedConversions

**Reproduction line:**
```
./gradlew ':x-pack:plugin:esql:qa:server:single-node:javaRestTest' --tests "org.elasticsearch.xpack.esql.qa.single_node.RestEsqlIT.testWarningHeadersOnFailedConversions" -Dtests.seed=849E06D41F81C775 -Dtests.locale=id-ID -Dtests.timezone=Pacific/Funafuti -Druntime.java=20
```

**Applicable branches:**
main

**Reproduces locally?:**
Didn't try

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.esql.qa.single_node.RestEsqlIT&tests.test=testWarningHeadersOnFailedConversions

**Failure excerpt:**
```
java.lang.AssertionError: 
Expected: is <21>
     but: was <0>

  at __randomizedtesting.SeedInfo.seed([849E06D41F81C775:98FDFE231D426DAD]:0)
  at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:18)
  at org.junit.Assert.assertThat(Assert.java:956)
  at org.junit.Assert.assertThat(Assert.java:923)
  at org.elasticsearch.xpack.esql.qa.rest.RestEsqlTestCase.testWarningHeadersOnFailedConversions(RestEsqlTestCase.java:256)
  at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
  at java.lang.reflect.Method.invoke(Method.java:578)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:48)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:843)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:490)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:850)
  at java.lang.Thread.run(Thread.java:1623)

```
x-pack/plugin/esql/qa/server/src/main/java/org/elasticsearch/xpack/esql/qa/rest/RestEsqlTestCase.java
RequestOptions.Builder options = request.getOptions().toBuilder();
        options.setWarningsHandler(WarningsHandler.PERMISSIVE); 
        options.addHeader("Content-Type", mediaType);
        if (randomBoolean()) {
            options.addHeader("Accept", mediaType);
        } else {
            request.addParameter("format", requestObject.contentType().queryParameter());
        }
        request.setOptions(options);
        HttpEntity entity = performRequest(request, expectedWarnings);
        try (InputStream content = entity.getContent()) {
            XContentType xContentType = XContentType.fromMediaType(entity.getContentType().getValue());
            assertEquals(requestObject.contentType(), xContentType);
            return XContentHelper.convertToMap(xContentType.xContent(), content, false);
        }
    }
    static String runEsqlAsTextWithFormat(RequestObjectBuilder builder, String format, @Nullable Character delimiter) throws IOException {
        Request request = prepareRequest();
        String mediaType = attachBody(builder, request);
        RequestOptions.Builder options = request.getOptions().toBuilder();
        options.addHeader("Content-Type", mediaType);
        if (randomBoolean()) {
            request.addParameter("format", format);
        } else {
            switch (format) {
                case "txt" -> options.addHeader("Accept", "text/plain");
                case "csv" -> options.addHeader("Accept", "text/csv");
                case "tsv" -> options.addHeader("Accept", "text/tab-separated-values");
            }
        }