[Review] Fix concurrent group access to prevent NullPointerException

[AncD8972]

Mirrored from ai-code-review-evaluation#10.

Test 10

[AncD8972]

🤖 DiffCOT AI Code Review

The PR adds a null check in GroupAdapter.getSubGroupsCount() to prevent NPE during concurrent group access, adds an @OverRide annotation, removes unused code, and adds a concurrency test.

Assessment	Score
⚠️ REQUEST_CHANGES	7/10

✅ Positive Aspects

• Good defensive programming by adding null check to prevent NPE in concurrent scenarios
• The test properly simulates concurrent access patterns that could trigger the original bug
• Clean removal of unused method in GroupUtils improves code maintainability
• Adding @OverRide annotation improves code clarity and enables compiler checking

💡 Suggestions for Improvement

• Consider adding @nullable annotation to getSubGroupsCount() if null return is intentional
• Consider making the concurrency test more robust by adding assertions about expected behavior
• Document why modelSupplier.get() can return null in this specific scenario

🔍 Issues Found: 3

• 🔴 High: 0
• 🟡 Medium: 2
• 🟢 Low: 1

See inline comments below for details.

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Generated by DiffCOT AI Code Review

[AncD8972]

🟡 MEDIUM | bug

Returning null from getSubGroupsCount() when model is null may cause NPE in callers that expect a Long value. This is a defensive fix but shifts the NPE risk to callers.

💡 Suggestion: Consider returning 0L instead of null, or document the null return value with @nullable annotation.

Suggested change

	GroupModel model = modelSupplier.get();
	return model == null ? null : model.getSubGroupsCount();
	GroupModel model = modelSupplier.get();
	return model == null ? 0L : model.getSubGroupsCount();

[AncD8972]

🟢 LOW | typo

Variable name 'groupUuuids' has an extra 'u' - should be 'groupUuids'.

💡 Suggestion: Fix the typo in variable name.

Suggested change

	public void createMultiDeleteMultiReadMulti() {
	List<String> groupUuids = new ArrayList<>();

[AncD8972]

🟡 MEDIUM | logic_defect

The test creates a thread but never joins it, which could cause the test to finish before the thread completes, making the test unreliable.

💡 Suggestion: Store the thread reference and join it after setting deletedAll to true.

Suggested change

	}
	}
	Thread readerThread = new Thread(() -> {
	while (!deletedAll.get()) {
	try {
	// just loading briefs
	managedRealm.admin().groups().groups(null, 0, Integer.MAX_VALUE, true);
	} catch (Exception e) {
	caughtExceptions.add(e);
	}
	}
	});
	readerThread.start();
	// delete groups
	groupUuuids.forEach(groupUuid -> {
	managedRealm.admin().groups().group(groupUuid).remove();
	});
	deletedAll.set(true);
	try {
	readerThread.join(5000); // Wait max 5 seconds for thread to finish
	} catch (InterruptedException e) {
	Thread.currentThread().interrupt();
	}