Breaking change in Avro 1.12.1 affects parquet-avro users: logical types now deserialize to different Java types

Start with the issue's AVRO-3989 link and the ReflectData, SpecificData, and GenericRecord behavior described here; no parquet-java file or test is named. Compare Avro 1.12.0 and 1.12.1 handling for the listed logical types, then determine with maintainers what change or documentation is expected before defining done.

Summary

Avro 1.12.1 introduces a breaking change that affects parquet-avro users. Multiple logical types are now deserialized to their proper Java types instead of their underlying primitive types when using ReflectData, causing ClassCastException in existing code.

Background

• Upstream issue: https://issues.apache.org/jira/browse/AVRO-3989
• Pull request: https://github.com/apache/avro/pull/3354
• Avro version affected: 1.12.1 (released as a patch version)

Problem

The fix in AVRO-3989 changed the deserialization behavior for ALL logical types. When using within parquet-avro ReflectData or SpecificData classes, these fields now return their logical Java type objects instead of their underlying primitive types from GenericRecord.

Affected logical types and conversions:

This breaks existing code that expects primitive values:

// This used to work in Avro 1.12.0
Long timestamp = (Long) genericRecord.get("timestamp_field");
Integer date = (Integer) genericRecord.get("date_field");
String uuid = (String) genericRecord.get("uuid_field");

// In Avro 1.12.1, all of these throw ClassCastException
// because values are now Instant, LocalDate, UUID, etc.

Impact

• Widespread breakage: Affects anyone using parquet-avro with ANY logical types
• Code that has worked for years suddenly breaks after a patch version update
• The breaking nature wasn't clearly documented in Avro's changelog
• This is a significant behavior change that affects the entire logical type system

Heads up for future avro updates

I apologize if this isn't the right place to report this, please feel free to redirect me if there's a better venue for this discussion. My main goal is to ensure that when parquet-java does consider updating Avro, the team and users are aware of this significant behavioral change.

For Current Users

If you're using parquet-avro and explicitly upgrading Avro to 1.12.1+ in your project, be aware of this breaking change. You'll need to update code that reads logical type fields from GenericRecord.