private static SimpleDateFormat buildUTCFormatter() {
    SimpleDateFormat formatter = new SimpleDateFormat(PUBLISHED_FILE_NAME_DATE_FORMAT);
    formatter.setTimeZone(TimeZone.getTimeZone("UTC"));
    return formatter;
  }
This method closes all DataFileWriters and output streams associated with all the blobs created.
flush should be explicitly called before close.
{@inheritDoc}
@throws IllegalStateException when closing a closed writer
@throws SamzaException if underlying DataFileWriter.close fails
samza-azure/src/main/java/org/apache/samza/system/azureblob/avro/AzureBlobAvroWriter.java