[Bug] Proxy lite client offline cleanup indexes empty subscriptions

[Aias00]

Before Creating the Bug Report

• I have searched the existing issues and pull requests.

Runtime platform environment

All platforms.

RocketMQ version

develop branch.

JDK Version

Not applicable.

Describe the Bug

GrpcClientSettingsManager.offlineClientLiteSubscription assumes a lite consumer's cached Settings always has at least one subscription entry:

String topic = settings.getSubscription().getSubscriptions(0).getTopic().getName();
String group = settings.getSubscription().getGroup().getName();

If a lite consumer has incomplete settings, for example ClientType.LITE_PUSH_CONSUMER with no subscription entries, this path throws an IndexOutOfBoundsException. The exception is caught by the broad catch block, but the cleanup path then logs an error with the full settings object and skips the offline cleanup through an exceptional path.

Steps to Reproduce

1. Build Settings with clientType = LITE_PUSH_CONSUMER.
2. Do not add any subscription entries.
3. Call GrpcClientSettingsManager.offlineClientLiteSubscription(ctx, clientId, settings).
4. The method tries to read getSubscriptions(0) before validating the count.

What Did You Expect to See?

Incomplete or malformed lite-consumer settings should be ignored by the offline cleanup path before indexing into the subscription list. No IndexOutOfBoundsException should be needed for control flow.

What Did You See Instead?

The method relies on the catch block after getSubscriptions(0) throws IndexOutOfBoundsException, and logs the full settings object at error level.

Additional Context

This is a small Proxy gRPC runtime cleanup hardening issue. It keeps client disconnect/offline handling from producing noisy error logs for incomplete settings and avoids logging full settings unnecessarily.

[RockteMQ-AI]

Issue Evaluation

Category: type/bug | Status: Confirmed

The reported issue has been verified against the current codebase.

Root Cause: GrpcClientSettingsManager.offlineClientLiteSubscription() at line 241 directly accesses settings.getSubscription().getSubscriptions(0) without checking if the subscriptions list is empty. When a lite consumer has incomplete settings (e.g., ClientType.LITE_PUSH_CONSUMER with no subscription entries), this throws IndexOutOfBoundsException.

Impact: Proxy gRPC client disconnect/offline handling produces noisy error logs for incomplete settings. The broad catch block logs the full settings object at error level, which is both a log pollution issue and a potential information leak.

Severity: low — No data loss or functional impact; the exception is caught and the cleanup is skipped via the exceptional path.

Suggested Fix: Add an empty-check on getSubscriptionsList() before indexing, and return early if the list is empty. Avoid logging the full settings object in the error path.

An automated fix proposal will be generated. Reply /approve to proceed with PR generation.

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Automated evaluation by RockteMQ-AI