docs: @BetaApi
    public final Operation abandonInstancesRegionInstanceGroupManager(
        ProjectRegionInstanceGroupManagerName instanceGroupManager,
        RegionInstanceGroupManagersAbandonInstancesRequest
            regionInstanceGroupManagersAbandonInstancesRequestResource) {
  
      AbandonInstancesRegionInstanceGroupManagerHttpRequest request =
          AbandonInstancesRegionInstanceGroupManagerHttpRequest.newBuilder()
              .setInstanceGroupManager(
                  instanceGroupManager == null ? null : instanceGroupManager.toString())
              .setRegionInstanceGroupManagersAbandonInstancesRequestResource(
                  regionInstanceGroupManagersAbandonInstancesRequestResource)
              .build();
      return abandonInstancesRegionInstanceGroupManager(request);
    }