code: @BetaApi
    public final InstanceGroupManager getInstanceGroupManager(String instanceGroupManager) {
  
      GetInstanceGroupManagerHttpRequest request =
          GetInstanceGroupManagerHttpRequest.newBuilder()
              .setInstanceGroupManager(instanceGroupManager)
              .build();
      return getInstanceGroupManager(request);
    }
docs: Returns all of the details about the specified managed instance group. Gets a list of available
  managed instance groups by making a list() request.
  
  <p>Sample code:
  
  <pre><code>
  try (InstanceGroupManagerClient instanceGroupManagerClient = InstanceGroupManagerClient.create()) {
  ProjectZoneInstanceGroupManagerName instanceGroupManager = ProjectZoneInstanceGroupManagerName.of("[PROJECT]", "[ZONE]", "[INSTANCE_GROUP_MANAGER]");
  InstanceGroupManager response = instanceGroupManagerClient.getInstanceGroupManager(instanceGroupManager.toString());
  }
  </code></pre>
  
  @param instanceGroupManager The name of the managed instance group.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails