code: @Override
  	protected void validateComponent(final List<Diagnostic> diags) {
  		if (isValidDate()) {
  			super.validateComponent(diags);
  		} else {
  			diags.add(createErrorDiagnostic(getComponentModel().errorMessage, this));
  		}
  	}
docs: Override WInput's validateComponent to perform further validation on the date. A partial date is invalid if there
  was text submitted but no date components were parsed.
  
  @param diags the list into which any validation diagnostics are added.