@Override
    public void onBlobCreated(String blobId, BlobProperties blobProperties, Account account, Container container,
        NotificationBlobType notificationBlobType) {
      blobCreatedEvents.computeIfAbsent(blobId, k -> new ArrayList<>())
          .add(new BlobCreatedEvent(blobProperties, notificationBlobType));
    }
A notification system for testing that keeps track of data from onBlobCreated calls.
ambry-router/src/test/java/com/github/ambry/router/PutManagerTest.java