code: func ValidateIngressUpdate(ingress, oldIngress *networking.Ingress) field.ErrorList {
  	allErrs := apivalidation.ValidateObjectMetaUpdate(&ingress.ObjectMeta, &oldIngress.ObjectMeta, field.NewPath("metadata"))
  	allErrs = append(allErrs, ValidateIngressSpec(&ingress.Spec, field.NewPath("spec"))...)
  	return allErrs
  }
docs: // ValidateIngressUpdate tests if required fields in the Ingress are set.