Feature request for DLQ strategy.

[javadevmtl]

As per my conversation with @cescoffier here: https://quarkusio.zulipchat.com/#narrow/stream/294206-smallrye/topic/Suggestion.20for.20DLQ.20strategy.2E/near/300863081

Currently when a message is DLQ, the headers contain the following info as an example:

{
	"dead-letter-reason": "Connection refused: localhost/127.0.0.1:18080",
	"dead-letter-offset": "98",
	"dead-letter-partition": "124",
	"dead-letter-cause": "Connection refused",
	"dead-letter-topic": "webhook-push-dlr-dev"
}

When creating consumers to read the dead letter topic and you want to create some sort of processing logic, you need to compare string messages. This is isn't the most ideal situation because you need to compare string text and you also need to know the exact text coming from the the exception.

That said it would be nice to have an additional header, with the class name of the exception. This makes it easier/safer to compare and also deal with.

{
	"dead-letter-exception": "com.java.net.ConnectionException.class",
	"dead-letter-reason": "Connection refused: localhost/127.0.0.1:18080",
	"dead-letter-offset": "98",
	"dead-letter-partition": "124",
	"dead-letter-cause": "Connection refused",
	"dead-letter-topic": "webhook-push-dlr-dev"
}

Which means now we can do this:

if("com.java.net.ConnectionException".equals(Headers.get("dead-letter-exception"))

or

if("com.abc.MyCustomRetriableException".equals(Headers.get("dead-letter-exception"))

instead of

if("Connection refused".equalsIgnoreCase(Headers.get("dead-letter-cause"))