private function validateAndDetermineStrategy()
    {
        if (extension_loaded('grpc')) {
            return;
        }

        require_once dirname(__FILE__) . '/grpc.stubs.php';

        // force the h2proxy strategy
        $strategy = $this->config->getStrategy();
        if (!is_a($strategy, H2ProxyStrategy::class)) {
            $h2ProxyConfig = new H2ProxyConfig();
            $h2ProxyStrategy = (new H2ProxyStrategyFactory($h2ProxyConfig))->build();
            $this->config->setStrategy($h2ProxyStrategy);
        }
    }