private function namespaceFromLegacyNamespace($namespace, $className)
    {
        $qcn = str_replace('_', '\\', $className);

        $lastBackslash = strrpos($qcn, '\\');
        if ($lastBackslash) {
            $namespace = rtrim($namespace, '\\') . '\\' . substr($qcn, 0, $lastBackslash);
        }

        return $namespace;
    }