Trace ID logging inconsistencies across kafka binder and reactor kafka binder

Hi,

I have created the prototype https://github.com/davidmelia/spring-boot-kafka-consumer-tracing to illustrate an issue summarised by

• Trace ID is output OK in the kafka binder depending on where the log statement is in the reactor chain.
• Trace ID is not output in the reactor kafka binder

If you follow the README after hitting http://localhost:8080/sendMessage you will see

...  INFO [aid=spring-boot-kafka-consumer-tracing,tid=,sid=,cusname=] 36173 --- [-f567995d3b2a-1] c.e.demo.consumer.TestMessagesConsumer   : Reactor Kafka Binder: This log statement does not have the trace id

...  INFO [aid=spring-boot-kafka-consumer-tracing,tid=63e4bb48fde4e7bad38152c80451f3e1,sid=7a6ca04b1324a87c,cusname=My Name] 36173 --- [container-0-C-1] c.e.demo.consumer.TestMessagesConsumer   : Kafka Binder: This log statement has the trace id

...  INFO [aid=spring-boot-kafka-consumer-tracing,tid=,sid=,cusname=] 36173 --- [     parallel-4] c.e.demo.consumer.TestMessagesConsumer   : Reactor Kafka Binder: This log statement does not have the trace id

...  INFO [aid=spring-boot-kafka-consumer-tracing,tid=,sid=,cusname=] 36173 --- [     parallel-5] c.e.demo.consumer.TestMessagesConsumer   : Kafka Binder: This log statement does not have the trace id

I have found no way to get the reactor kafka binder to log the trace ID nor can I get the following statement to log the trace ID in any binder

return Mono.just("OK").delayElement(Duration.ofMillis(10)).doOnSuccess(r -> log.info(...);

Thanks

Start with the linked prototype README and reproduce the behavior by calling http://localhost:8080/sendMessage. Compare trace-ID logging in the Kafka binder and Reactor Kafka binder, including the delayed Mono case; done means the affected log statements consistently include the trace ID or the limitation is documented.