Duplicate headers

[Rajh]

Hello,

Why KafkaHeaders.EXCEPTION_CAUSE_FQCN is equal to KafkaHeaders.EXCEPTION_FQCN ? Is it a typo ?

spring-kafka/spring-kafka/src/main/java/org/springframework/kafka/support/KafkaHeaders.java

Line 252 in c0e210c

public static final String EXCEPTION_CAUSE_FQCN = PREFIX + "exception-fqcn";

spring-kafka/spring-kafka/src/main/java/org/springframework/kafka/support/KafkaHeaders.java

Line 246 in c0e210c

public static final String EXCEPTION_FQCN = PREFIX + "exception-fqcn";

And why having 2 sets of headers for DLT (DeadLetterPublishingRecoverer and @RetryableTopic DLT) ?
KafkaHeaders.DLT_EXCEPTION_CAUSE_FQCN KafkaHeaders.EXCEPTION_CAUSE_FQCN

[garyrussell]

Thanks; fixed. The DLT_ headers are for "classic" (blocking) retries with the default DeadLetterPublishingRecoverer.

The ones without the DLT_ are for non-blocking retries; they don't have DLT in the name because the intermediate topics are not dead letter topics, they are delayed retry topics.

There's an argument that says the final publish to the retryable topic DLT should have the DLT prefix but they don't.

Bottom line; use the DLT_ headers when not using retryable topics and the others when you are.