The fourth milestone for the next Spring Data generation has been released, bringing new features and upgrades. A significant change is the updated default MongoDB UUID format, which now uses BSON binary subtype 4 instead of the legacy subtype 3. This alteration means existing data stored with subtype 3 may not be read correctly without migration or reverting to the old default. The team is considering removing all defaults for explicit configuration to prevent future surprises. Spring Data R2DBC now supports composite identifiers and embeddables, allowing for complex types as identifiers. An example demonstrates how to use records for composite IDs in R2DBC. The project also aims to include Jackson 3 support in the next milestone. Release notes offer a complete list of all changes and contributions. The milestone versions for various Spring Data projects, including Commons, JPA, Neo4j, Cassandra, MongoDB, and others, are also listed.