// This field is required in all cases.
  optional string namespace = 1;

  // Name is the metadata.name of the referenced ConfigMap.
  // This field is required in all cases.
  optional string name = 2;

  // UID is the metadata.UID of the referenced ConfigMap.
  // This field is forbidden in Node.Spec, and required in Node.Status.
  // +optional
  optional string uid = 3;