code: func validateContainersOnlyForPod(containers []core.Container, fldPath *field.Path) field.ErrorList {
  	allErrs := field.ErrorList{}
  	for i, ctr := range containers {
  		idxPath := fldPath.Index(i)
  		if len(ctr.Image) != len(strings.TrimSpace(ctr.Image)) {
  			allErrs = append(allErrs, field.Invalid(idxPath.Child("image"), ctr.Image, "must not have leading or trailing whitespace"))
  		}
  	}
  	return allErrs
  }
docs: // validateContainersOnlyForPod does additional validation for containers on a pod versus a pod template
  // it only does additive validation of fields not covered in validateContainers