// +patchStrategy=merge
  optional string key = 1;

  // operator represents a key's relationship to a set of values.
  // Valid operators are In, NotIn, Exists and DoesNotExist.
  optional string operator = 2;

  // values is an array of string values. If the operator is In or NotIn,
  // the values array must be non-empty. If the operator is Exists or DoesNotExist,