test: poll for shutDownCalled in startWithHttp401ShutsDownSink test (SDK-2028)

[devin-ai-integration]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

• SDK-2028 — Flaky test: StreamingDataSourceTest.startWithHttp401ShutsDownSink race condition
• Observed on PR chore: Update sdk_metadata features #328

Describe the solution you've provided

The startWithHttp401ShutsDownSink test is flaky due to a race condition. In StreamingDataSource.onError(), the production code calls resultCallback.onError() (which unblocks the test's callback.awaitError()) before calling dataSourceUpdateSink.shutDown(). The test thread can resume and assert shutDownCalled before the background thread reaches the shutDown() call.

This PR adds a short polling loop (up to 1 second, checking every 10ms) to wait for shutDownCalled to become true before asserting. This is a test-only change — no production code is modified.

Key review points:

• shutDownCalled is declared volatile in MockDataSourceUpdateSink (line 141 of MockComponents.java), so cross-thread visibility is guaranteed
• The 1-second timeout is generous for what should complete in microseconds; the 10ms poll interval avoids busy-waiting
• Sibling tests that assert assertFalse(shutDownCalled) are not affected by this race since shutDown() is never called in those code paths

Describe alternatives you've considered

Approach 2 (not used): Reorder production code in StreamingDataSource.onError() to call shutDown() before resultCallback.onError(). This would fix the root cause but changes production behavior and carries more risk. Per team discussion, Approach 1 (test-only fix) was chosen as the safer option.

Additional context

The Android SDK is required to compile/run tests locally, so this change relies on CI for validation.

Link to Devin session: https://app.devin.ai/sessions/c61d7f41a5ec43208840f81363097b09

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Note

Low Risk
Low risk test-only change that adds a short wait to avoid a race between the background thread reporting the error and shutting down the update sink.

Overview
Fixes a flaky StreamingDataSourceTest.startWithHttp401ShutsDownSink by waiting (up to 1s, polling) for dataSourceUpdateSink.shutDownCalled to become true before asserting.

No production behavior changes; this only adjusts the test’s timing expectations for the async shutdown path after an HTTP 401.

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