Parameter gkeCredentials should be optional, but isn't

[thallgren]

The input parameter gkeCredentials is claimed to be optional. However, failing to provide this parameter yields the following error:

Error: gkeCredentials are missing. Make sure that input parameter gkeCredentials was provided
    at new Client (/home/runner/work/_actions/datawire/infra-actions/v0.2.0/provision-cluster/lib/gke.js:35:15)
    at Object.<anonymous> (/home/runner/work/_actions/datawire/infra-actions/v0.2.0/provision-cluster/lib/registry.js:10:10)

The reason for this is that the when the const distributions declared in registry.js is initialized, it calls on the gke.Client constructor, which in turn produces the error.

[thallgren]

The workaround I used to circumvent the problem was to provide a dummy credential that names a service. That works, because it is never used:

    gkeCredentials: '{"project_id": "foo"}'