MINOR: Extract HeartbeatRequestState from heartbeat request managers

[cadonna]

The AbstractHeartbeatRequestManager and the
StreamsGroupHeartbeatRequestManager, both use the
HeartbeatRequestState to track the state of the heartbeat requests. Both heartbeat request managers have an implementation of HeartbeatRequestState as inner class.
To deduplicate code this commit extracts the HeartbeatRequestState so that the same code can be used by both heartbeat request manager.

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[cadonna]

Call for review: @aliehsaeedii

PR Overview

This PR deduplicates heartbeat request state management by extracting the HeartbeatRequestState from its duplicated inner class implementations into a dedicated file. Key changes include:

• Extraction of HeartbeatRequestState into its own file.
• Updates to heartbeat request managers and their tests to reference the new HeartbeatRequestState.
• Removal of outdated inner class definitions from the AbstractHeartbeatRequestManager and StreamsGroupHeartbeatRequestManager.

Reviewed Changes

File	Description
HeartbeatRequestState.java	New file extracting heartbeat state logic.
HeartbeatRequestStateTest.java	Unit tests covering the new HeartbeatRequestState behavior.
ShareHeartbeatRequestManagerTest.java	Updated tests to use the extracted HeartbeatRequestState.
AbstractHeartbeatRequestManager.java	Updated to invoke heartbeatIntervalMs() instead of using a field directly.
StreamsGroupHeartbeatRequestManager.java	Removed obsolete inner class and updated heartbeatIntervalMs usage.
ConsumerHeartbeatRequestManager.java	Updated import and type references to the new HeartbeatRequestState.
ConsumerHeartbeatRequestManagerTest.java	Removed import of the now-obsolete inner class.

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

clients/src/main/java/org/apache/kafka/clients/consumer/internals/AbstractHeartbeatRequestManager.java:181

• The change to invoke heartbeatIntervalMs() improves clarity; please ensure that this getter method remains consistently used across all heartbeat managers.

return new NetworkClientDelegate.PollResult(heartbeatRequestState.heartbeatIntervalMs(), Collections.singletonList(leaveHeartbeat));

[kirktrue]

Thanks for the PR @cadonna!

This looks like a pretty simple refactoring. Just the one question about the Javadoc comment in the new, top-level class.

Thanks!

[kirktrue]

Is there supposed to be another line after "The two fields that it holds are:", or is it implying the reader looks at the class instance variables?

[cadonna]

Oh, I did not notice that! Thanks!

I do not have an answer to your question. Also the old code had that. I will remove the last sentence.