fix: implicity nullable parameter deprecations

Author: JorickPepin

src/Extractor/FromSourceMappingExtractor.php

@@ -51,7 +51,7 @@ public function getTypes(string $source, SourcePropertyMetadata $sourceProperty,
         return $types;
     }
 
-    private function transformType(string $target, Type $type = null): ?Type
+    private function transformType(string $target, ?Type $type = null): ?Type
     {
         if (null === $type) {
             return null;

src/Metadata/MetadataFactory.php

@@ -326,8 +326,8 @@ public static function create(
         MetadataRegistry $metadataRegistry,
         ClassDiscriminatorResolver $classDiscriminatorResolver,
         array $transformerFactories = [],
-        ClassMetadataFactory $classMetadataFactory = null,
-        AdvancedNameConverterInterface $nameConverter = null,
+        ?ClassMetadataFactory $classMetadataFactory = null,
+        ?AdvancedNameConverterInterface $nameConverter = null,
         ExpressionLanguage $expressionLanguage = new ExpressionLanguage(),
         EventDispatcherInterface $eventDispatcher = new EventDispatcher(),
     ): self {

src/php-parser.php

@@ -37,7 +37,7 @@ function create_scalar_int(int $value, array $attributes = []): Scalar\Int_|Scal
  *
  * @internal
  */
-function create_expr_array_item(Expr $value, Expr $key = null, bool $byRef = false, array $attributes = [], bool $unpack = false): Node\ArrayItem|Expr\ArrayItem
+function create_expr_array_item(Expr $value, ?Expr $key = null, bool $byRef = false, array $attributes = [], bool $unpack = false): Node\ArrayItem|Expr\ArrayItem
 {
     $class = class_exists(Node\ArrayItem::class) ? Node\ArrayItem::class : Expr\ArrayItem::class;