PayPal\Auth\Oauth\OAuthServer::get_version PHP Method

    private function get_version(&$request)
    {
        $version = $request->get_parameter("oauth_version");
        if (!$version) {
            // Service Providers MUST assume the protocol version to be 1.0 if this parameter is not present.
            // Chapter 7.0 ("Accessing Protected Ressources")
            $version = '1.0';
        }
        if ($version !== $this->version) {
            throw new OAuthException("OAuth version '{$version}' not supported");
        }
        return $version;
    }