GH-3001: default clientIds with application name

[notizklotz]

Fixes: #GH-3001

Use Spring Boot's spring.application.name property as part of the default clientIds for Consumers, Producers and AdminClients. Helps with identifying problematic clients at server side.

• Only use as a fallback if clientId wasn't specified explicitly
• Do not use for Consumers with a specified groupId because KafkaConsumer will use the groupId as clientId which already is an identifiable default

[sobychacko]

@notizklotz I am Starting to review the PR. There are some build failures due to checkstyle issues. See here.
Also, you need to add some docs about these changes.

[notizklotz]

@notizklotz I am Starting to review the PR. There are some build failures due to checkstyle issues. See here. Also, you need to add some docs about these changes.

@sobychacko I fixed the checkstyle errors and added some docs to the "What’s new?" section

[sobychacko]

@notizklotz Thanks. The problem with adding this in the whats-new doc is that this will be replaced for the next version (3.3.0). This deserves a separate small section inside the reference docs. Maybe add a new section for configuring client.id? Then a short sentence in the whats-new section. One other thing - can you add your name as the @author in all the classes you modified and update any copyright years?

[notizklotz]

@sobychacko Added section to reference docs, added author tag, checked copyright years, squashed commits and rebased to upstream main

[sobychacko]

Thanks @notizklotz for the updates. One last comment - What do you think about extracting spring.application.name text literal into a common property since it is repeated in a handful of places?

[notizklotz]

Thanks @notizklotz for the updates. One last comment - What do you think about extracting spring.application.name text literal into a common property since it is repeated in a handful of places?

@sobychacko I considered that but decided against it, because I couldn't find an existing class where I think it would be a good fit. I didn't want to introduce a new class like "Constants" just for this literal. I also saw that the "client-id" literal is also copy/pasted across various classes and I thought to stick with the existing style.

[sobychacko]

Fair enough. We can always refactor that later if need be.