@Override
    public NacosGrpcProtocolNegotiator build() {
        Properties properties = EnvUtil.getProperties();
        RpcServerTlsConfig config = RpcServerTlsConfigFactory.getInstance().createSdkConfig(properties);
        if (config.getEnableTls()) {
            SslContext sslContext = DefaultTlsContextBuilder.getSslContext(config);
            return new OptionalTlsProtocolNegotiator(sslContext, config);
        }
        return null;
    }
@Test
    void testBuildDisabled() {
        assertNull(builder.build());
    }