[KAFKA-14162] HoistField and MaskField SMTs should not return immutable maps/lists

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.4.0
• Component/s: connect
• Assignee: Yash Mayya
• Reporter: Yash Mayya
• Reviewer: Chris Egerton
• Created: 11/Aug/22 08:20
• Updated: 23/Aug/22 14:22
• Resolved: 23/Aug/22 14:22

Description

The HoistField SMT currently returns an immutable map for schemaless keys and values - https://github.com/apache/kafka/blob/22007fba7c7346c5416f4db4e104434fdab265ee/connect/transforms/src/main/java/org/apache/kafka/connect/transforms/HoistField.java#L62.

 

This can cause issues in connectors if they attempt to modify the SourceRecord's key or value since Kafka Connect doesn't document that these keys/values are immutable. Furthermore, no other SMT does this.

 

An example of a connector that would fail when schemaless values are used with this SMT is Microsoft's Cosmos DB Sink Connector - https://github.com/microsoft/kafka-connect-cosmosdb/blob/368566367a1dcbf9a91213067f1b9219a530bb16/src/main/java/com/azure/cosmos/kafka/connect/sink/CosmosDBSinkTask.java#L123-L130

Issue Links

• links to: GitHub Pull Request #12502