**Build scan:**
https://gradle-enterprise.elastic.co/s/ol67zg6nlufds/tests/:modules:ingest-common:test/org.elasticsearch.ingest.common.SetProcessorTests/testSetExistingFields

**Reproduction line:**
```
./gradlew ':modules:ingest-common:test' --tests "org.elasticsearch.ingest.common.SetProcessorTests.testSetExistingFields" -Dtests.seed=8970DEFD8FE56CF -Dtests.locale=ga -Dtests.timezone=Pacific/Pitcairn -Druntime.java=20
```

**Applicable branches:**
main

**Reproduces locally?:**
Yes

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.ingest.common.SetProcessorTests&tests.test=testSetExistingFields

**Failure excerpt:**
```
java.lang.IllegalArgumentException: Can't pick a random object from an empty collection.

  at __randomizedtesting.SeedInfo.seed([8970DEFD8FE56CF:C4B1BF9A3C989B34]:0)
  at com.carrotsearch.randomizedtesting.generators.RandomPicks.randomFrom(RandomPicks.java:50)
  at org.elasticsearch.ingest.RandomDocumentPicks.randomExistingFieldName(RandomDocumentPicks.java:72)
  at org.elasticsearch.ingest.common.SetProcessorTests.testSetExistingFields(SetProcessorTests.java:37)
  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)

```
test/framework/src/main/java/org/elasticsearch/ingest/RandomDocumentPicks.java
return true;
                }
                if (currentLevel instanceof Map == false) {
                    return false;
                }
                @SuppressWarnings("unchecked")
                Map<String, Object> map = (Map<String, Object>) currentLevel;
                innerMap = map;
            }
        }
        String leafKey = pathElements[pathElements.length - 1];
        return innerMap.containsKey(leafKey) == false;
    }
    /**
     * Generates a random document and random metadata
     */
    public static IngestDocument randomIngestDocument(Random random) {
        return randomIngestDocument(random, randomSource(random));
    }
    /**
     * Generates a document that holds random metadata and the document provided as a map argument
     */
    public static IngestDocument randomIngestDocument(Random random, Map<String, Object> source) {
        String index = randomString(random);
        String id = randomString(random);
        String routing = null;
        Long version = randomNonNegtiveLong(random);
        VersionType versionType = RandomPicks.randomFrom(
            random,
            new VersionType[] { VersionType.INTERNAL, VersionType.EXTERNAL, VersionType.EXTERNAL_GTE }