public static String serialize(S3MultipartETag eTag) throws IOException {
    ObjectNode rootObject = objectMapper.createObjectNode();

    PutBlobMetaInfo metaInfo = new PutBlobMetaInfo(eTag.getOrderedChunkIdSizeList(), null);
    ObjectNode chunks = PutBlobMetaInfo.serializeToJsonObject(metaInfo);
    rootObject.put(DATA_CHUNK_LIST, chunks);
    rootObject.put(VERSION, CURRENT_VERSION);

    return Base64.encodeBase64URLSafeString(rootObject.toString().getBytes());
  }
Serialize the {@link S3MultipartETag} to Json string
@return the serialized Json string
ambry-api/src/main/java/com/github/ambry/frontend/s3/S3MultipartETag.java