code: public static String addQueryParameters(String url, String... kvPairs) {
          String queryDelim = url.contains("?") ? "&" : "?";
          StringBuilder sb = new StringBuilder(url + queryDelim);
          for (int i = 0; i < kvPairs.length; i += 2) {
              if (i > 0) {
                  sb.append("&");
              }
              sb.append(OAuth.percentEncode(kvPairs[i]) + "="
                      + OAuth.percentEncode(kvPairs[i + 1]));
          }
          return sb.toString();
      }
docs: Appends a list of key/value pairs to the given URL, e.g.:
  
  <pre>
  String url = OAuth.addQueryParameters(&quot;http://example.com?a=1&quot;, b, 2, c, 3);
  </pre>
  
  which yields:
  
  <pre>
  http://example.com?a=1&b=2&c=3
  </pre>
  
  All parameters will be encoded according to OAuth's percent encoding
  rules.
  
  @param url
  the URL
  @param kvPairs
  the list of key/value pairs
  @return