@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 testBuildEnabled() {
        try (final MockedStatic<EnvUtil> envUtilMockedStatic = Mockito.mockStatic(EnvUtil.class)) {
            when(EnvUtil.getProperties()).thenReturn(properties);
            when(properties.getProperty("nacos.remote.server.rpc.tls.enableTls")).thenReturn("true");
            when(properties.getProperty("nacos.remote.server.rpc.tls.certPrivateKey")).thenReturn("test-server-key.pem");
            when(properties.getProperty("nacos.remote.server.rpc.tls.certChainFile")).thenReturn("test-server-cert.pem");
            assertNotNull(builder.build());
        }
    }