docs: @Override
      public String extract(OAuthRequest request) {
          checkPreconditions(request);
          final String verb = OAuthEncoder.encode(getVerb(request));
          final String url = OAuthEncoder.encode(getUrl(request));
          final String params = getSortedAndEncodedParams(request);
          return String.format(AMPERSAND_SEPARATED_STRING, verb, url, params);
      }