title: How to get Hex value from computeHmacSha256Signature method of Google Apps Script?
body: <p>I read solution for MD5 below, but I could not quite get it.<br>
  <a href="https://stackoverflow.com/questions/16216868/get-back-a-string-representation-from-computedigestalgorithm-value-byte">get back a string representation from computeDigest(algorithm, value) byte[]</a>  </p>
  
  <p>I'd like to create API signature with HMAC-SHA256 hash.</p>
  
  <pre><code>var date = new Date();
  var nonce = Math.floor(date.getTime()/1000);
  var url = "https://mysweet.com/api/accounts"
  var secret = "my_secret";
  var signature = Utilities.computeHmacSha256Signature(nonce+url, secret);
  </code></pre>
  
  <p>but it returns byte array [42, -8, -47, -21, ..], and it cannot be used as API signature directly.
  Is there a simple way to get a Hex value from the method? or conversion?</p>