Issue #3500212: Use attributes for LengthValidator plugin

Related to #3500212

src/Plugin/FapiValidationValidator/LengthValidator.php

@@ -3,17 +3,20 @@
 namespace Drupal\fapi_validation\Plugin\FapiValidationValidator;
 
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+use Drupal\fapi_validation\Attribute\FapiValidationValidator;
 use Drupal\fapi_validation\FapiValidationValidatorsInterface;
 use Drupal\fapi_validation\Validator;
 
 /**
  * Fapi Validation Plugin for Length validation.
- *
- * @FapiValidationValidator(
- *   id = "length",
- *   error_message = "Invalid size of %field value."
- * )
  */
+#[FapiValidationValidator(
+  id: 'length',
+  label: new TranslatableMarkup('Length'),
+  description: new TranslatableMarkup('Validate input value length.'),
+  error_message: 'Invalid size of %field value.',
+)]
 class LengthValidator implements FapiValidationValidatorsInterface {
 
   /**