private BlobId createBlobId(String hexBlobId) throws IOException {
    if (hexBlobId == null) {
      return null;
    }
    return new BlobId(hexBlobId, clusterMap);
  }
Tests using the transformer with Message inputs that have null components
@throws Exception
ambry-replication/src/test/java/com/github/ambry/replication/BlobIdTransformerTest.java