Transform FunctionFactoryTests. testCreateLatestFunction fails

[benwtrent]

Build scan:
https://gradle-enterprise.elastic.co/s/jpxhkvlcqq3ze
Repro line:

./gradlew ':x-pack:plugin:transform:test' --tests "org.elasticsearch.xpack.transform.transforms.FunctionFactoryTests.testCreateLatestFunction" -Dtests.seed=98F3DDD081D6BC00 -Dtests.security.manager=true -Dtests.locale=ko-KR -Dtests.timezone=Europe/Ljubljana -Druntime.java=11

Reproduces locally?:
Yes
Applicable branches:
master

Failure excerpt:

org.elasticsearch.xpack.transform.transforms.FunctionFactoryTests > testCreateLatestFunction FAILED |  
-- | --
  | java.lang.IllegalArgumentException: Composite source names must be unique, found duplicates: [O] |  
  | at __randomizedtesting.SeedInfo.seed([98F3DDD081D6BC00:A0E95A82E5AC2FFF]:0) |  
  | at org.elasticsearch.search.aggregations.bucket.composite.CompositeAggregationBuilder.validateSources(CompositeAggregationBuilder.java:202) |  
  | at org.elasticsearch.search.aggregations.bucket.composite.CompositeAggregationBuilder.<init>(CompositeAggregationBuilder.java:79) |  
  | at org.elasticsearch.search.aggregations.AggregationBuilders.composite(AggregationBuilders.java:379) |  
  | at org.elasticsearch.xpack.transform.transforms.latest.Latest.createCompositeAggregation(Latest.java:80) |  
  | at org.elasticsearch.xpack.transform.transforms.latest.Latest.<init>(Latest.java:68) |  
  | at org.elasticsearch.xpack.transform.transforms.FunctionFactory.create(FunctionFactory.java:30) |  
  | at org.elasticsearch.xpack.transform.transforms.FunctionFactoryTests.testCreateLatestFunction(FunctionFactoryTests.java:38)

[elasticmachine]

Pinging @elastic/ml-core (:ml/Transform)