@Override
        public void onBlobUndeleted(String blobId, String serviceId, Account account, Container container) {
          blobsThatAreUndeleted.add(blobId);
          undeletesDoneLatch.countDown();
        }
Test undelete notification system when successfully undelete a blob.
@throws Exception
ambry-router/src/test/java/com/github/ambry/router/NonBlockingRouterTest.java