private int getNumReplicas(String blobId) {
    try {
      BlobId blobIdObj = new BlobId(blobId, clusterMap);
      PartitionId partitionId = blobIdObj.getPartition();
      return partitionId.getReplicaIds().size();
    } catch (Exception e) {
      throw new IllegalArgumentException("Invalid blob ID: " + blobId, e);
    }
  }
@param blobId the blob ID received
@return the number of replicas of {@code blobId}
ambry-test-utils/src/main/java/com/github/ambry/server/MockNotificationSystem.java