code: @BetaApi
    public final ListInstanceGroupManagersPagedResponse listInstanceGroupManagers(String zone) {
      ListInstanceGroupManagersHttpRequest request =
          ListInstanceGroupManagersHttpRequest.newBuilder().setZone(zone).build();
      return listInstanceGroupManagers(request);
    }
docs: Retrieves a list of managed instance groups that are contained within the specified project and
  zone.
  
  <p>Sample code:
  
  <pre><code>
  try (InstanceGroupManagerClient instanceGroupManagerClient = InstanceGroupManagerClient.create()) {
  ProjectZoneName zone = ProjectZoneName.of("[PROJECT]", "[ZONE]");
  for (InstanceGroupManager element : instanceGroupManagerClient.listInstanceGroupManagers(zone.toString()).iterateAll()) {
  // doThingsWith(element);
  }
  }
  </code></pre>
  
  @param zone The name of the zone where the managed instance group is located.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails