code: protected function getOauthParameters()
      {
          $time = time();
  
          return array(
              'oauth_consumer_key' => $this->getConsumerKey(),
              'oauth_nonce' => trim(base64_encode($time), '='),
              'oauth_signature_method' => 'HMAC-SHA1',
              'oauth_timestamp' => $time,
              'oauth_token' => $this->getAccessToken(),
              'oauth_version' => '1.0'
          );
      }
docs: Getting OAuth parameters to be used in request headers
  
  @return array  OAuth parameters