long getBlobSize() {
    if (!chunkFillingCompletedSuccessfully) {
      throw new IllegalStateException("Request for blob size before chunk fill completion");
    }
    return blobSize;
  }
@return the size of the blob in this operation. This method should only be called once the chunk filling has
completed (which is when the final size is determined).
@throws IllegalStateException if the chunk filling has not yet completed.
ambry-router/src/main/java/com/github/ambry/router/PutOperation.java