code: @BetaApi
    public final Operation setInstanceTemplateInstanceGroupManager(
        String instanceGroupManager,
        InstanceGroupManagersSetInstanceTemplateRequest
            instanceGroupManagersSetInstanceTemplateRequestResource) {
  
      SetInstanceTemplateInstanceGroupManagerHttpRequest request =
          SetInstanceTemplateInstanceGroupManagerHttpRequest.newBuilder()
              .setInstanceGroupManager(instanceGroupManager)
              .setInstanceGroupManagersSetInstanceTemplateRequestResource(
                  instanceGroupManagersSetInstanceTemplateRequestResource)
              .build();
      return setInstanceTemplateInstanceGroupManager(request);
    }
docs: Specifies the instance template to use when creating new instances in this group. The templates
  for existing instances in the group do not change unless you recreate them.
  
  <p>Sample code:
  
  <pre><code>
  try (InstanceGroupManagerClient instanceGroupManagerClient = InstanceGroupManagerClient.create()) {
  ProjectZoneInstanceGroupManagerName instanceGroupManager = ProjectZoneInstanceGroupManagerName.of("[PROJECT]", "[ZONE]", "[INSTANCE_GROUP_MANAGER]");
  InstanceGroupManagersSetInstanceTemplateRequest instanceGroupManagersSetInstanceTemplateRequestResource = InstanceGroupManagersSetInstanceTemplateRequest.newBuilder().build();
  Operation response = instanceGroupManagerClient.setInstanceTemplateInstanceGroupManager(instanceGroupManager.toString(), instanceGroupManagersSetInstanceTemplateRequestResource);
  }
  </code></pre>
  
  @param instanceGroupManager The name of the managed instance group.
  @param instanceGroupManagersSetInstanceTemplateRequestResource
  @throws com.google.api.gax.rpc.ApiException if the remote call fails