Abort resend when send() returns false

[Copilot]

Implement resend abort when send() returns false

• Explore the codebase and understand the resend flow
• Modify the resendMessages method in Session.java to check the return value of send() and abort if it returns false
• Add a warning log message when resend is aborted
• Create and verify unit test that demonstrates the new behavior
• Run SessionTest suite (71 tests) - all pass
• Perform code review
• Address review feedback: Use session log (getLog().onWarnEvent) instead of static LOG.warn
• Address review feedback: Add JavaDoc comment for test method
• Address review feedback: Fix issue reference to use GitHub issue URL format
• Complete implementation

Original prompt

Implement a change in the QuickFIX/J codebase so that resend operations abort when send(String messageString) returns false. Add a warning log message when this condition occurs. Also add a unit test that demonstrates the new behavior (i.e., resending stops/aborts after the first failed send).

Context:

• GitHub Issue: Stop sending resend-messages when the responder has gone away #646 ("Stop sending resend-messages when the responder has gone away")
• Current behavior: resend continues even when send() returns false / no responder.

Acceptance criteria:

1. During a resend loop/batch, if send(String messageString) returns false, abort any further resends for that resend request.
2. Emit a warning log entry when the resend is aborted due to send() returning false.
3. Add/adjust a unit test that fails on current behavior and passes with the fix; the test should set up a resend scenario where send() returns false partway (or immediately) and assert that subsequent resend attempts are not performed.
4. Ensure existing behavior remains unchanged when send() returns true.
5. Keep the change minimal and localized to resend-related code paths.

This pull request was created from Copilot chat.

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[chrjohn]

CI job currently failing due to #1120 , waiting for fix.

[chrjohn]

@copilot this comment should be removed and the correct issue should be added as a method comment.

[Copilot]

Removed inline comment and added proper JavaDoc method comment for QFJ-646 in commit 6c07eae.