NIFI-14630 Corrected usage of KafkaClientComponent interface

[turcsanyip]

The PR removes KafkaPublishComponent / KafkaClientComponent interface implementation from PublishKafka. The single property that was used from KafkaPublishComponent has been moved to the processor (as other publisher specific properties).
Kafka3ConnectionService now implements KafkaClientComponent in order for the properties be defined in a single location. The properties in the interface have been updated from the controller service (they were used from the service effectively, the interface just provided property names for the shared code).

Summary

NIFI-14630

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[mark-bathori]

Thanks @turcsanyip for these fixes and corrections. The changes looks good.
LGTM +1

[pvillard31]

Any reason for not keeping this validator and the default value?

[turcsanyip]

Thanks for flagging this!

In general, I did not want to change the behavior of the properties in order to eliminate compatibility issues at all. So I took the property definitions from Kafka3ConnectionService because those were used effectively.

On the other hand, it makes sense to add HOSTNAME_PORT_LIST_VALIDATOR because the existing Bootstrap Servers property values must be following this format already. Otherwise the property is unusable. So this seems a minimal risk change and therefore I'm leaning toward adding the validator.

Regarding localhost:9092 default value: The "localhost" values are typically used during development only and they must be changed in real life use cases almost all the time. Personally, I don't prefer "developer defaults" exposed in prod apps (even if it is handy for devs). However, I see that we use "localhost" defaults in some places so if you think it is kind of a convention in NiFi, I can add it.

So I'm +1 for the validator and rather -1 for the default value. Please share what you think based on the background info provided above and I will change the code accordingly.

[pvillard31]

Yep, fair enough, sounds good to me, thanks @turcsanyip

[exceptionfactory]

I agree with removing the localhost:9092 default value, and instead having it null is best, thanks @turcsanyip and @pvillard31.

[pvillard31]

Thanks @turcsanyip - I had another look at the changes and I'm a +1
@exceptionfactory - feel free to merge if you're a +1 as well or I can do it

[exceptionfactory]

Thanks @turcsanyip, and thanks for the review @pvillard31, I concur with the changes. +1 merging