xero-google-script-v2.gs

    var oauth_nonce = createGuid();
    var oauth_timestamp = (new Date().getTime()/1000).toFixed();
    var signBase = 'GET' + '&' + encodeURIComponent(requestURL) + '&' +
      encodeURIComponent( complexQuery + '&oauth_consumer_key=' + CONSUMER_KEY + '&oauth_nonce=' + 
                         oauth_nonce + '&oauth_signature_method=' + oauth_signature_method + '&oauth_timestamp=' +
                         oauth_timestamp + '&oauth_token=' + CONSUMER_KEY + '&oauth_version=' + oauth_version + '&page=' + pageNo);
    
    var hSig = rsa.signString(signBase, hashAlg);
    
    var oauth_signature = encodeURIComponent(hextob64(hSig));  
    var authHeader = "OAuth oauth_token=\"" + CONSUMER_KEY + "\",oauth_nonce=\"" + oauth_nonce + 
      "\",oauth_consumer_key=\"" + CONSUMER_KEY + "\",oauth_signature_method=\"RSA-SHA1\",oauth_timestamp=\"" +
        oauth_timestamp + "\",oauth_version=\"1.0\",oauth_signature=\"" + oauth_signature + "\"";
    
    var headers = { "Authorization": authHeader, "Accept": "application/json"};    
    var options = { 'muteHttpExceptions': true, "headers": headers}; 
    var response = UrlFetchApp.fetch(requestURL + '?' + complexQuery + '&page=' + pageNo, options);