The `OSDelegatingFileTailingMessageProducer` publishes event from scheduled task * Modify `FileTailingMessageProducerTests.testGuts()` to use `CountDownLatch` to wait for those asynchronous events **Cherry-pick to `6.1.x`**
The `OSDelegatingFileTailingMessageProducer` publishes event from scheduled task * Modify `FileTailingMessageProducerTests.testGuts()` to use `CountDownLatch` to wait for those asynchronous events **Cherry-pick to `6.1.x`**