**Build scan:**
https://gradle-enterprise.elastic.co/s/fvg2knbi424p4/tests/:x-pack:plugin:esql:test/org.elasticsearch.xpack.esql.expression.function.scalar.conditional.LeastTests/testEvaluateInManyThreads%20%7BTestCase=(%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E)%20null%20in%204%7D
**Reproduction lines:**
```
gradlew ':x-pack:plugin:esql:test' --tests "org.elasticsearch.xpack.esql.expression.function.scalar.conditional.GreatestTests.testEvaluateInManyThreads {TestCase=(<mv_integer>) null in 0}" -Dtests.seed=BCCD8A2AFCEA37CB -Dtests.locale=zh -Dtests.timezone=Europe/Guernsey -Druntime.java=21

gradlew ':x-pack:plugin:esql:test' --tests "org.elasticsearch.xpack.esql.expression.function.scalar.conditional.LeastTests.testEvaluateInManyThreads {TestCase=(<keyword>, <keyword>, <keyword>, <keyword>, <keyword>, <keyword>, <keyword>) null in 4}" -Dtests.seed=BCCD8A2AFCEA37CB -Dtests.locale=lt -Dtests.timezone=Indian/Christmas -Druntime.java=21

 gradlew ':x-pack:plugin:esql:test' --tests "org.elasticsearch.xpack.esql.expression.function.scalar.conditional.GreatestTests.testEvaluateInManyThreads {TestCase=(<mv_integer>) null in 0}" -Dtests.seed=BCCD8A2AFCEA37CB -Dtests.locale=zh -Dtests.timezone=Europe/Guernsey -Druntime.java=21
```

**Applicable branches:**
main

**Reproduces locally?:**
Yes

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.esql.expression.function.scalar.conditional.LeastTests&tests.test=testEvaluateInManyThreads%20%7BTestCase%3D(%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E,%20%3Ckeyword%3E)%20null%20in%204%7D


**Failure excerpt:**
```
org.elasticsearch.xpack.esql.expression.function.scalar.conditional.GreatestTests > classMethod FAILED
    java.lang.AssertionError: expected:<[boolean, double, integer, ip, keyword, long, text, version]> but was:<[integer]>


```
x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/AbstractFunctionTestCase.java
|===
            """ + header + "\n" + table.stream().collect(Collectors.joining("\n")) + "\n|===\n";
        LogManager.getLogger(getTestClass()).info("Writing function types:\n{}", rendered);
        writeToTempDir("types", rendered, "asciidoc");
    }
    private static FunctionDefinition definition() {
        String name = functionName();
        EsqlFunctionRegistry registry = new EsqlFunctionRegistry();
        if (registry.functionExists(name)) {
            return registry.resolveFunction(name);
        }
        return null;
    }
    private static String functionName() {
        return StringUtils.camelCaseToUnderscore(getTestClass().getSimpleName().replace("Tests", "")).toLowerCase(Locale.ROOT);
    }
    /**
     * Write some text to a tempdir so we can copy it to the docs later.
     * <p>
     *     We need to write to a tempdir instead of the docs because the tests
     *     don't have write permission to the docs.
     * </p>
     */
    private static void writeToTempDir(String subdir, String str, String extension) throws IOException {
        
        Path dir = PathUtils.get(System.getProperty("java.io.tmpdir")).resolve("esql").resolve("functions").resolve(subdir);
        Files.createDirectories(dir);
        Path file = dir.resolve(functionName() + "." + extension);
        Files.writeString(file, str);
    }