code: func dropDisabledRunAsGroupField(podSpec, oldPodSpec *api.PodSpec) {
  	if !utilfeature.DefaultFeatureGate.Enabled(features.RunAsGroup) && !runAsGroupInUse(oldPodSpec) {
  		if podSpec.SecurityContext != nil {
  			podSpec.SecurityContext.RunAsGroup = nil
  		}
  		for i := range podSpec.Containers {
  			if podSpec.Containers[i].SecurityContext != nil {
  				podSpec.Containers[i].SecurityContext.RunAsGroup = nil
  			}
  		}
  		for i := range podSpec.InitContainers {
  			if podSpec.InitContainers[i].SecurityContext != nil {
  				podSpec.InitContainers[i].SecurityContext.RunAsGroup = nil
  			}
  		}
  	}
  }
docs: // dropDisabledRunAsGroupField removes disabled fields from PodSpec related
  // to RunAsGroup