Add IsSet to SetterDefinition for kyaml release.

kyaml/setters2/add.go

@@ -172,6 +172,9 @@ type SetterDefinition struct {
 	// live apply/preview. This field is added to the setter definition to record
 	// the package publisher's intent to make the setter required to be set.
 	Required bool `yaml:"required,omitempty"`
+
+	// IsSet indicates the specified field has been explicitly assigned.
+	IsSet bool `yaml:"isSet,omitempty"`
 }
 
 func (sd SetterDefinition) AddToFile(path string) error {