code: private String makeNonce(String timestamp) {
  		byte[] bytes = new byte[10];
  		random.nextBytes(bytes);
  		StringBuilder sb = new StringBuilder(timestamp);
  		sb.append("-");
  		for (int i = 0; i < bytes.length; ++i) {
  			String b = Integer.toHexString(bytes[i] & 0xff);
  			if (b.length() < 2) {
  				sb.append("0");
  			}
  			sb.append(b);
  		}
  		return sb.toString();
  	}
docs: Generates a nonce for a request using a secure random number generator
  @param timestamp the request's timestamp (generated by {@link #makeTimestamp()})
  @return the nonce