Error running demo

[yejunyu]

Environment

• Dubbo version: master
• Operating System version: 4.9.0-deepin13-amd64 不同的group应该是不同的注册中心 #1 SMP PREEMPT Deepin 4.9.57-1 (2017-10-19) x86_64 GNU/Linux
• Java version: 1.8.0_161

Step to reproduce this issue

if i didn't write <dubbo:provider server="netty4"></dubbo:provider> in dubbo-demo-provider.xml,
this program will report an error

https://github.com/apache/incubator-dubbo/tree/master/dubbo-demo/

If there is an exception, please attach the exception trace:

[diecui1202]

In my local env, it works only with adding -Djava.net.preferIPv4Stack=true to vm args.

@yejunyu u can check it again. Make sure your local repo is clean.

[diecui1202]

Pls. feel free to reopen if necessary.