Instructions in jdk-example are outdated - gcloud alpha Version "1.7.8-gke.0" is invalid.

[anthonydahanne]

When running this command in the tutorial :

 gcloud --project=$ISTIO_PROJECT_ID alpha container clusters create istio-cluster   --zone=us-central1-c --num-nodes=4 --machine-type=n1-standard-4   --cluster-version=1.7.8-gke.0 --enable-kubernetes-alpha

I got :

WARNING: You invoked `gcloud alpha`, but with current configuration Kubernetes Engine v1 API will be used instead of v1alpha1 API.
`gcloud alpha` will switch to use Kubernetes Engine v1alpha1 API by default by the end of March 2018.
If you want to keep using `gcloud alpha` to talk to v1 API temporarily, please set `container/use_v1_api` property to true.
But we will drop the support for this property at the beginning of May 2018, please migrate if necessary.
Kubernetes Engine v1alpha1 API is for whitelist-only at the moment.
If you want to use it, please make sure your project is whitelisted.
This will create a cluster with all Kubernetes Alpha features enabled.
- This cluster will not be covered by the Kubernetes Engine SLA and
should not be used for production workloads.
- You will not be able to upgrade the master or nodes.
- The cluster will be deleted after 30 days.

Do you want to continue (Y/n)?  Y

ERROR: (gcloud.alpha.container.clusters.create) ResponseError: code=400, message=Version "1.7.8-gke.0" is invalid.