private static char[] buildClientPassword(Token<BlockTokenIdentifier> blockToken) {
    return Base64.getEncoder().encodeToString(blockToken.getPassword()).toCharArray();
  }
Create a ByteString from byte array without copying (wrap), and then set it as the payload
for the builder.
@param builder builder for HDFS DataTransferEncryptorMessage.
@param payload byte array of payload.
hbase-asyncfs/src/main/java/org/apache/hadoop/hbase/io/asyncfs/FanOutOneBlockAsyncDFSOutputSaslHelper.java