void updateContainerBucket(Long bucketKey, short accountId, short containerId, long value) {
    if (bucketKey != null && containerDeltaBuckets.containsKey(bucketKey)) {
      Map<Short, Map<Short, Long>> existingBucketEntry = containerDeltaBuckets.get(bucketKey);
      updateNestedMapHelper(existingBucketEntry, accountId, containerId, value);
    }
  }
Helper function to update a container bucket with the given value.
@param bucketKey the bucket key to specify which bucket will be updated
@param accountId the accountId of the map entry to be updated
@param containerId the containerId of the map entry to be updated
@param value the value to be added
ambry-store/src/main/java/com/github/ambry/store/ScanResults.java