[blakeli0]

SubscriberTest.testStreamAckDeadlineIsSetCorrectly starts and stops four subscribers in a row against one FakeSubscriberServiceImpl, and it is flaky.

subscriber.stopAsync().awaitTerminated() only waits for the client side. The fake removes a stream from its list of opened streams later, when its server thread sees the client's cancellation. If the next subscriber starts before that happens, the fake is still tracking the previous stream and the test fails in one of two ways:

• expected:<1> but was:<2>: the old and the new stream are both counted as open.
• A stale stream ack deadline such as expected:<600> but was:<10>: only the old stream is listed so far, so getLastSeenRequest() returns the previous subscriber's request.

This change waits for the fake to record each closed stream (waitForClosedStreams) before starting the next subscriber. It only touches the test.

Verification

Run locally on JDK 25:

	Test as on main	With this change
6,000 runs of the test method	17 failures, with both signatures above	0 failures
5 runs with a 200 ms delay temporarily added to the fake's close handling (local experiment, not in this PR)	5 failures	0 failures

SubscriberTest passes (13 tests) and fmt-maven-plugin:check is clean for google-cloud-pubsub.

The failure was seen in ci / split-units (java-pubsub, 8): https://github.com/googleapis/google-cloud-java/actions/runs/41130804887/job/124321665889. The stale-deadline variant was reported for this test in googleapis/java-pubsub#682.

b/580634974

[gemini-code-assist]

Code Review

This pull request updates SubscriberTest.java by adding calls to fakeSubscriberServiceImpl.waitForClosedStreams() after terminating the subscriber. This ensures that the fake server asynchronously registers that the stream was closed before proceeding, preventing assertions from incorrectly counting old streams. I have no feedback to provide as there are no review comments.