Issue while using golang

Hi,
I got this issue while building example code : 

> cannot find module for path github.com/Azure/azure-sdk-for-go/services/containerinstance/mgmt/2017-08-01-preview/containerinstance

On Azure repo we have : 
```
2018-04-01/containerinstance	
2018-06-01/containerinstance	
2018-09-01/containerinstance	
2018-10-01/containerinstance
```