Braintree\Util::camelCaseToDelimiter PHP Метод

    public static function camelCaseToDelimiter($string, $delimiter = '-')
    {
        return strtolower(preg_replace('/([A-Z])/', "{$delimiter}\\1", $string));
    }

 private function _underscoreKeys($array)
 {
     foreach ($array as $key => $value) {
         $newKey = Util::camelCaseToDelimiter($key, '_');
         unset($array[$key]);
         if (is_array($value)) {
             $array[$newKey] = $this->_underscoreKeys($value);
         } else {
             $array[$newKey] = $value;
         }
     }
     return $array;
 }