code: public static String joinURIQuery(Map<String, String> uriParams) {
          StringBuilder buffer = new StringBuilder();
          for (String name : uriParams.keySet()) {
              String value = uriParams.get(name);
              if (buffer.length() > 0) {
                  buffer.append("&");
              }
              buffer.append(Utils.urlEncode(name));
              if (!Utils.isEmpty(value)) {
                  buffer.append("=");
                  buffer.append(Utils.urlEncode(value));
              }
          }
          return buffer.toString();
      }
docs: Concatenate and encode the given name/value pairs into a valid URI query string.
  This method is the complement of {@link #parseURIQuery(String)}.
  
  @param uriParams Unencoded name/value pairs.
  @return          URI query in the form {name 1}={value 1}{@literal &}...{@literal &}{name}={value n}.