com.alibaba.dubbo.rpc.RpcException: Failed to invoke the method sayHello in the service com.yu.service.DubboApi. No provider available for the service dubbodemo/com.yu.service.DubboApi from registry 127.0.0.1:2181 on the consumer 10.68.26.216 using the dubbo version 2.6.9. Please check if the providers have been started and registered.