goldpinger does not support v6 ping

[paulyufan2]

Describe the bug
I am trying to use goldpinger to test ipv6 connectivity between pods in Azure. I add "IP_VERSIONS" to my deployment yaml file:

    spec:
        containers:
          - name: goldpinger
            env:
              - name: HOST
                value: "0.0.0.0"
              - name: PORT
                value: "8080"
              **- name: IP_VERSIONS
                value: "6"**

When I start testing, I found from goldpingerClient to get clusterState, it does not contain ipv6 address and it only does ipv4 ping. When I read goldpinger library, I see podResult only takes ipv4 address, so it will not do ipv6 test for podResult:
https://github.com/bloomberg/goldpinger/blob/master/pkg/goldpinger/pinger.go#L77

Can anyone help check if we already support this feature or not and if so, how we can use it?

Thanks!

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**Expected behavior**
ipv6 ping should get executed

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