protected function convertStaticPhpExcelConstantsFromStringsToConstants($value)
    {
        if (strpos($value, 'PHPExcel_') === 0) {
            $parts = explode('::', $value);
            $class = new \ReflectionClass($parts[0]);
            $value = $class->getConstant($parts[1]);
        }

        return $value;
    }