The DLQ metadata contains four mandatory fields and one optional field all as JSON key / value pairs:

original_headers. This is a repeated field containing all the Kafka headers present in the original message.

original_topic. This is a single string whose value is the topic that the original message was consumed from.

original_consumer_group. This is a single string whose value is the consumer group used by the consumer which encountered the error while processing the message.

original_timestamp. This is a single string whose value is the timestamp of when the original message was created.

stack_trace. This is an optional single string field which, if present, will contain the processing error.