code: func serveDefaultColumnsIfEmpty(columns []CustomResourceColumnDefinition) []CustomResourceColumnDefinition {
  	if len(columns) > 0 {
  		return columns
  	}
  	return []CustomResourceColumnDefinition{
  		{Name: "Age", Type: "date", Description: swaggerMetadataDescriptions["creationTimestamp"], JSONPath: ".metadata.creationTimestamp"},
  	}
  }
docs: // serveDefaultColumnsIfEmpty applies logically defaulting to columns, if the input columns is empty.
  // NOTE: in this way, the newly logically-defaulted columns is not pointing to the original CRD object.
  // One cannot mutate the original CRD columns using the logically-defaulted columns. Please iterate through
  // the original CRD object instead.