@Override
    public void onBlobCreated(String blobId, BlobProperties blobProperties, Account account, Container container,
        NotificationBlobType notificationBlobType) {
      blobIdOperatedOn = blobId;
      operationCompleted.countDown();
    }
Latch for awaiting the completion of an operation.
ambry-rest/src/test/java/com/github/ambry/rest/NettyMessageProcessorTest.java