docs: @BetaApi
    public final Operation insertRegionInstanceGroupManager(
        ProjectRegionName region, InstanceGroupManager instanceGroupManagerResource) {
  
      InsertRegionInstanceGroupManagerHttpRequest request =
          InsertRegionInstanceGroupManagerHttpRequest.newBuilder()
              .setRegion(region == null ? null : region.toString())
              .setInstanceGroupManagerResource(instanceGroupManagerResource)
              .build();
      return insertRegionInstanceGroupManager(request);
    }