ThreadedStreamConsumer - use Thread.join() instead of CountDownLatch.await()

Currently, ThreadedStreamConsumer uses CountDownLatch.await() which is not 100% reliable. The thread may die if it is in the waiting state during shutdown period. Let's use Thread.join() in the close().
Attention: do NOT use Thread.join() in the method handleEvent() - too slow, and therefore we use AtomicBoolean as a treatment.