Validates a definedTag value. Each validator performs validation steps in addition to the standard
validation for definedTag values. For more information, see
Limits on Tags.
If you define a validator after a value has been set for a defined tag, then any updates that attempt to change the value must pass the additional validation defined by the current rule. Previously set values (even those that would fail the current validation) are not updated. You can still update other attributes to resources that contain a non-valid defined tag.
To clear the validator call UpdateTag with DefaultTagDefinitionValidator.
public class BaseTagDefinitionValidator : object