[Validator] Showcase custom validator constraint required option

Author: norkunas

validation/custom_constraint.rst

@@ -30,19 +30,35 @@ First you need to create a Constraint class and extend :class:`Symfony\\Componen
         {
             public $message = 'The string "{{ string }}" contains an illegal character: it can only contain letters or numbers.';
             public $mode = 'strict'; // If the constraint has configuration options, define them as public properties
+
+            public function getRequiredOptions(): array
+            {
+                return ['mode'];
+            }
         }
 
     .. code-block:: php-attributes
 
         // src/Validator/ContainsAlphanumeric.php
         namespace App\Validator;
 
+        use Symfony\Component\Validator\Attribute\HasNamedArguments;
         use Symfony\Component\Validator\Constraint;
 
         #[\Attribute]
         class ContainsAlphanumeric extends Constraint
         {
             public $message = 'The string "{{ string }}" contains an illegal character: it can only contain letters or numbers.';
+
+            public string $mode;
+
+            #[HasNamedArguments]
+            public function __construct(string $mode, array $groups = null, mixed $payload = null)
+            {
+                parent::__construct([], $groups, $payload);
+
+                $this->mode = $mode;
+            }
         }
 
 Add ``@Annotation`` or ``#[\Attribute]`` to the constraint class if you want to
@@ -271,7 +287,7 @@ not to the property:
         namespace App\Entity;
 
         use App\Validator as AcmeAssert;
-        
+
         /**
          * @AcmeAssert\ProtocolClass
          */