public boolean isRequired()
Returns true if any underlying org.apache.tapestry5.Validator  returns true from org.apache.tapestry5.Validator#isRequired() .

 public  void render(MarkupWriter writer)
Invokes Validator#render(Field, Object, org.apache.tapestry5.ioc.MessageFormatter, MarkupWriter,
org.apache.tapestry5.services.FormSupport) . This is called at a point "inside" the tag, so that additional
attributes may be added.  In many cases, the underlying org.apache.tapestry5.Validator  may write
client-side JavaScript to enforce the constraint as well.

 public  void validate(T value) throws ValidationException
Invoked after the client-submitted value has been translated  to check that the value conforms
to expectations (often, in terms of minimum or maximum value). If and only if the value is approved by all
Validators is the value applied by the field.