code: protected function createBaseString(Request $request, array $params)
      {
          // Remove query params from URL. Ref: Spec: 9.1.2.
          //TODO - remove params properly, not this hack method
          $request = clone $request;
  //        $request->setQueryFields([]);
  
          $uri = $request->getUri();
          $queryString = '';
          if ($questionMark = strpos($uri, '?')) {
              $uri = substr($uri, 0, $questionMark);
              $request->setUri($uri);
          }
  
  //        $url = $request->getUri();
          $query = http_build_query($params, '', '&', PHP_QUERY_RFC3986);
  
          return strtoupper($request->getMethod())
              . '&' . rawurlencode($uri)
              . '&' . rawurlencode($query);
      }
docs: Creates the Signature Base String.
  
  The Signature Base String is a consistent reproducible concatenation of
  the request elements into a single string. The string is used as an
  input in hashing or signing algorithms.
  
  @param \Amp\Artax\Request $request Request being signed
  @param array            $params  Associative array of OAuth parameters
  
  @return string Returns the base string
  @link http://oauth.net/core/1.0/#sig_base_example