description: matchLabels is a map of {key,value} pairs. A single
                        {key,value} in the matchLabels map is equivalent to an element
                        of matchExpressions, whose key field is "key", the operator
                        is "In", and the values array contains only "value". The requirements
                        are ANDed.
                      type: object
                  type: object

  // The only valid values for this field are 'Apply' and 'Update'.
  optional string operation = 2;

  // APIVersion defines the version of this resource that this field set
  // applies to. The format is "group/version" just like the top-level
  // APIVersion field. It is necessary to track the version of a field
  // set because it cannot be automatically converted.