[stevehu]

Migrate producer, consumer and Streams templates to auto.register.schemas with matching canonical values.yml placeholders and generated values entries. Related: networknt/light-kafka#264; light-example-4j is explicitly out of scope.

Document the required override rename: old Confluent settings were ignored; canonical false requests lookup-only and requires registered schemas. Preserve the deliberately supported Light serializer legacy fallback. Existing defaults remain true.

Validation: mvn -o -q -pl light-hybrid-4j -am -Dmaven.repo.local=/home/steve/workspace/artifacts/implementation/light-4j/jackson-3-migration/m2-phase5-baseline test passed 13 tests with no failures/errors/skips, including all eight Kafka flag combinations for both generators, exact correspondence between emitted configs and values entries, and canonical/old override injection; git diff --check passes. Local validation uses the preserved Jackson 2 cache. No Jackson 3 changes or deployment are included; remote CI remains separate.

The values template now receives the actual consumer/Streams file emission decisions, preserving the existing server consumer-flag-to-Streams behavior. Generated values and the README prominently require migration of old false overrides; no legacy alias is introduced.

[stevehu]

Review findings

These apply to the shared template changes. I verified the first one on the #738 branch, and 2.x has the same generator structure.

1. values.yml entries don't match the generated kafka ymls (values.rocker.raw)
HybridServerGenerator emits kafka-streams.yml when kafkaConsumer is true and never emits kafka-consumer.yml. With only kafkaConsumer=true, the server's kafka-streams.yml reads kafka-streams.auto.register.schemas, but values.yml only has kafka-consumer.auto.register.schemas. Setting that to false has no effect. With only kafkaStreams=true, values.yml has a dead entry. Please gate each entry on the same condition as its yml.

2. The old override key is silently ignored (kafkaProducerYml.rocker.raw, plus consumer and Streams)
An existing kafka-*.schema.registry.auto.register.schemas: false is no longer referenced, so the template falls back to true and begins auto-registering with no warning. Consider a fallback or a loud failure. This is a plausible risk, not reproduced.

3. Test (KafkaSchemaRegistrationGenerationTest)
It enables all three flags, so it hides item 1. The skip condition is convoluted, and assertTrue(values.contains(client + ".auto.register.schemas: true")) asserts the dead server kafka-consumer entry. The final direct consumer render check duplicates the service-folder assertions.