NIFI-15286 Add connection verification to Kafka Connection Services

[exceptionfactory]

Summary

NIFI-15286 Adds manual connection verification to Kafka Connection Services.

The implementation builds on the initial proposal in PR #10596 and provides the following approach:

1. Moves all verification methods to the new KafkaConnectionVerifier class with one reusable instance of the class for each instance of the Kafka Connection Service
2. Moves Topic Listing to the final verification step
3. Verifies address formatting before verifying socket connections
4. Verifies socket connections before Kafka Client connections

The implementation includes updated integration tests against Kafka running in a container to evaluate common failure and success paths.

Successful verification includes the following steps:

1. Broker Addresses displaying number of addresses validated
2. Node Connection displaying host and port for each Node with socket connection
3. Cluster Description displaying number of Nodes found
4. Topic Listing displaying the number of Topics found

Tracking

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Issue Tracking

• Apache NiFi Jira issue created

Pull Request Tracking

• Pull Request title starts with Apache NiFi Jira issue number, such as NIFI-00000
• Pull Request commit message starts with Apache NiFi Jira issue number, as such NIFI-00000

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Build

• Build completed using ./mvnw clean install -P contrib-check
  • JDK 21
  • JDK 25

Licensing

• New dependencies are compatible with the Apache License 2.0 according to the License Policy
• New dependencies are documented in applicable LICENSE and NOTICE files

Documentation

• Documentation formatting appears as expected in rendered files

[pvillard31]

Thanks @exceptionfactory, it is working as expected. Left two comments, happy to merge after that.

[pvillard31]

Should we use a thread-safe list here? Given that we have virtual threads that execute in parallel, we could have a ConcurrentModificationException, no?

[exceptionfactory]

Good catch, yes, I will wrap this in a synchronized List.

[pvillard31]

Suggested change

	.explanation("Addresses Validated [%d]".formatted(validatedAddresses.size()))
	.explanation("Addresses validated [%d]".formatted(validatedAddresses.size()))

To be consistent with, for example, "Topics found"

[exceptionfactory]

Thanks for the review @pvillard31, I pushed an update to synchronize the List and adjust the message capitalization.

[pvillard31]

Thanks, +1, will merge once checks are green (but likely tomorrow now - you can self merge before if you want)