code: protected function buildFilterUrl($fragments, $searchKey)
      {
          // @codingStandardsIgnoreStart
          @trigger_error(
              sprintf('"%1$s" has been deprecated in favor of the "FilterUrlBuilder"', __METHOD__),
              E_USER_DEPRECATED
          );
          // @codingStandardsIgnoreEnd
  
          $url   = '';
          $found = false;
  
          // Create base url containing for preserving the current filter on unrelated widgets and modules.
          // The URL parameter concerning us will be masked via %s to be used later on in a sprintf().
          foreach ($fragments as $key => $value) {
              // Skip the magic "language" parameter.
              if (($key == 'language') && $GLOBALS['TL_CONFIG']['addLanguageToUrl']) {
                  continue;
              }
  
              if ($key == $searchKey) {
                  if ($key !== 'auto_item') {
                      $url .= '%s';
                  } else {
                      $url = '%s' . $url;
                  }
                  $found = true;
              } else {
                  $url = $this->addUrlParameter($url, $key, $value);
              }
          }
  
          // If we have not found our parameter in the URL, we add it as %s now to be able to populate it via sprintf()
          // below.
          if (!$found) {
              if ($searchKey !== 'auto_item') {
                  $url .= '%s';
              } else {
                  $url = '%s' . $url;
              }
          }
  
          return $url;
      }
docs: Build the filter url based upon the fragments.
  
  @param array  $fragments The parameters to be used in the Url.
  
  @param string $searchKey The param key to handle for "this".
  
  @return string
  
  @SuppressWarnings(PHPMD.Superglobals)
  @SuppressWarnings(PHPMD.CamelCaseVariableName)
  
  @deprecated Not in use anymore, use the FilterUrlBuilder.