public static function extractHeaderAttributes($headers, $prefix = NULL) {
    if (empty($prefix)) {
      $prefix = Container::METADATA_HEADER_PREFIX;
    }
    $attributes = array();
    $offset = strlen($prefix);
    foreach ($headers as $header => $value) {

      $index = strpos($header, $prefix);
      if ($index === 0) {
        $key = substr($header, $offset);
        $attributes[$key] = $value;
      }
    }
    return $attributes;
  }