Environment details

• OS: macOS 10.15.7
• Node.js version: v12.18.4
• npm version: 6.14.6
• @google-cloud/container version: 2.2.0

Steps to reproduce

1. Given this async function:

const container = require('@google-cloud/container');
const client = new container.v1.ClusterManagerClient();
const {
  PROJECT, ZONE, CLUSTER, POOL,
} = process.env;
const config = {
  projectId: PROJECT,
  clusterId: CLUSTER,
  zone: ZONE,
  nodePoolId: POOL,
};
const turnOffCluster = async () => {
  const [operation] = await client.setNodePoolAutoscaling(
    { ...config, autoscaling: { enabled: false } },
  );
  await operation.promise();
  await client.setNodePoolSize({ ...config, nodeCount: 0 });
};
turnOffCluster();

2. When the function is executed an error is thrown:

(node:58270) UnhandledPromiseRejectionWarning: TypeError: operation.promise is not a function

Expected behaviour

The operation.promise() should return a promise as it is specified in the documentation https://googleapis.dev/nodejs/container/latest/v1.ClusterManagerClient.html#setNodePoolAutoscaling

We need that in order to be able to wait until the autoscaling is completely applied to later be able to resize the pool to 0.