diff -ruN a/Builder/ClassBuilder.php b/Builder/ClassBuilder.php
--- a/Builder/ClassBuilder.php	2026-07-15 12:28:18
+++ b/Builder/ClassBuilder.php	2026-07-15 12:28:18
@@ -119,7 +119,7 @@
         $this->methods[] = new Method(strtr($body, ['NAME' => $this->camelCase($name)] + $params));
     }
 
-    public function addProperty(string $name, string $classType = null, string $defaultValue = null): Property
+    public function addProperty(string $name, ?string $classType = null, ?string $defaultValue = null): Property
     {
         $property = new Property($name, '_' !== $name[0] ? $this->camelCase($name) : $name);
         if (null !== $classType) {
diff -ruN a/ConfigCacheInterface.php b/ConfigCacheInterface.php
--- a/ConfigCacheInterface.php	2026-07-15 12:28:18
+++ b/ConfigCacheInterface.php	2026-07-15 12:28:18
@@ -41,5 +41,5 @@
      *
      * @throws \RuntimeException When the cache file cannot be written
      */
-    public function write(string $content, array $metadata = null);
+    public function write(string $content, ?array $metadata = null);
 }
diff -ruN a/Definition/BaseNode.php b/Definition/BaseNode.php
--- a/Definition/BaseNode.php	2026-07-15 12:28:18
+++ b/Definition/BaseNode.php	2026-07-15 12:28:18
@@ -45,7 +45,7 @@
     /**
      * @throws \InvalidArgumentException if the name contains a period
      */
-    public function __construct(?string $name, NodeInterface $parent = null, string $pathSeparator = self::DEFAULT_PATH_SEPARATOR)
+    public function __construct(?string $name, ?NodeInterface $parent = null, string $pathSeparator = self::DEFAULT_PATH_SEPARATOR)
     {
         if (str_contains($name = (string) $name, $pathSeparator)) {
             throw new \InvalidArgumentException('The name must not contain ".'.$pathSeparator.'".');
diff -ruN a/Definition/Builder/ArrayNodeDefinition.php b/Definition/Builder/ArrayNodeDefinition.php
--- a/Definition/Builder/ArrayNodeDefinition.php	2026-07-15 12:28:18
+++ b/Definition/Builder/ArrayNodeDefinition.php	2026-07-15 12:28:18
@@ -40,7 +40,7 @@
     /**
      * {@inheritdoc}
      */
-    public function __construct(?string $name, NodeParentInterface $parent = null)
+    public function __construct(?string $name, ?NodeParentInterface $parent = null)
     {
         parent::__construct($name, $parent);
 
@@ -132,7 +132,7 @@
      *
      * @return $this
      */
-    public function addDefaultChildrenIfNoneSet(int|string|array $children = null): static
+    public function addDefaultChildrenIfNoneSet(int|string|array|null $children = null): static
     {
         $this->addDefaultChildren = $children;
 
@@ -175,7 +175,7 @@
      *
      * @return $this
      */
-    public function fixXmlConfig(string $singular, string $plural = null): static
+    public function fixXmlConfig(string $singular, ?string $plural = null): static
     {
         $this->normalization()->remap($singular, $plural);
 
diff -ruN a/Definition/Builder/BooleanNodeDefinition.php b/Definition/Builder/BooleanNodeDefinition.php
--- a/Definition/Builder/BooleanNodeDefinition.php	2026-07-15 12:28:18
+++ b/Definition/Builder/BooleanNodeDefinition.php	2026-07-15 12:28:18
@@ -24,7 +24,7 @@
     /**
      * {@inheritdoc}
      */
-    public function __construct(?string $name, NodeParentInterface $parent = null)
+    public function __construct(?string $name, ?NodeParentInterface $parent = null)
     {
         parent::__construct($name, $parent);
 
diff -ruN a/Definition/Builder/ExprBuilder.php b/Definition/Builder/ExprBuilder.php
--- a/Definition/Builder/ExprBuilder.php	2026-07-15 12:28:18
+++ b/Definition/Builder/ExprBuilder.php	2026-07-15 12:28:18
@@ -35,7 +35,7 @@
      *
      * @return $this
      */
-    public function always(\Closure $then = null): static
+    public function always(?\Closure $then = null): static
     {
         $this->ifPart = function () { return true; };
 
@@ -53,7 +53,7 @@
      *
      * @return $this
      */
-    public function ifTrue(\Closure $closure = null): static
+    public function ifTrue(?\Closure $closure = null): static
     {
         if (null === $closure) {
             $closure = function ($v) { return true === $v; };
diff -ruN a/Definition/Builder/NodeBuilder.php b/Definition/Builder/NodeBuilder.php
--- a/Definition/Builder/NodeBuilder.php	2026-07-15 12:28:18
+++ b/Definition/Builder/NodeBuilder.php	2026-07-15 12:28:18
@@ -39,7 +39,7 @@
      *
      * @return $this
      */
-    public function setParent(ParentNodeDefinitionInterface $parent = null): static
+    public function setParent(?ParentNodeDefinitionInterface $parent = null): static
     {
         $this->parent = $parent;
 
diff -ruN a/Definition/Builder/NodeDefinition.php b/Definition/Builder/NodeDefinition.php
--- a/Definition/Builder/NodeDefinition.php	2026-07-15 12:28:18
+++ b/Definition/Builder/NodeDefinition.php	2026-07-15 12:28:18
@@ -38,7 +38,7 @@
     protected $parent;
     protected $attributes = [];
 
-    public function __construct(?string $name, NodeParentInterface $parent = null)
+    public function __construct(?string $name, ?NodeParentInterface $parent = null)
     {
         $this->parent = $parent;
         $this->name = $name;
diff -ruN a/Definition/Builder/NormalizationBuilder.php b/Definition/Builder/NormalizationBuilder.php
--- a/Definition/Builder/NormalizationBuilder.php	2026-07-15 12:28:18
+++ b/Definition/Builder/NormalizationBuilder.php	2026-07-15 12:28:18
@@ -35,7 +35,7 @@
      *
      * @return $this
      */
-    public function remap(string $key, string $plural = null): static
+    public function remap(string $key, ?string $plural = null): static
     {
         $this->remappings[] = [$key, null === $plural ? $key.'s' : $plural];
 
@@ -47,7 +47,7 @@
      *
      * @return ExprBuilder|$this
      */
-    public function before(\Closure $closure = null): ExprBuilder|static
+    public function before(?\Closure $closure = null): ExprBuilder|static
     {
         if (null !== $closure) {
             $this->before[] = $closure;
diff -ruN a/Definition/Builder/TreeBuilder.php b/Definition/Builder/TreeBuilder.php
--- a/Definition/Builder/TreeBuilder.php	2026-07-15 12:28:18
+++ b/Definition/Builder/TreeBuilder.php	2026-07-15 12:28:18
@@ -23,7 +23,7 @@
     protected $tree;
     protected $root;
 
-    public function __construct(string $name, string $type = 'array', NodeBuilder $builder = null)
+    public function __construct(string $name, string $type = 'array', ?NodeBuilder $builder = null)
     {
         $builder = $builder ?? new NodeBuilder();
         $this->root = $builder->node($name, $type)->setParent($this);
diff -ruN a/Definition/Builder/ValidationBuilder.php b/Definition/Builder/ValidationBuilder.php
--- a/Definition/Builder/ValidationBuilder.php	2026-07-15 12:28:18
+++ b/Definition/Builder/ValidationBuilder.php	2026-07-15 12:28:18
@@ -31,7 +31,7 @@
      *
      * @return ExprBuilder|$this
      */
-    public function rule(\Closure $closure = null): ExprBuilder|static
+    public function rule(?\Closure $closure = null): ExprBuilder|static
     {
         if (null !== $closure) {
             $this->rules[] = $closure;
diff -ruN a/Definition/Dumper/XmlReferenceDumper.php b/Definition/Dumper/XmlReferenceDumper.php
--- a/Definition/Dumper/XmlReferenceDumper.php	2026-07-15 12:28:18
+++ b/Definition/Dumper/XmlReferenceDumper.php	2026-07-15 12:28:18
@@ -27,12 +27,12 @@
 {
     private ?string $reference = null;
 
-    public function dump(ConfigurationInterface $configuration, string $namespace = null)
+    public function dump(ConfigurationInterface $configuration, ?string $namespace = null)
     {
         return $this->dumpNode($configuration->getConfigTreeBuilder()->buildTree(), $namespace);
     }
 
-    public function dumpNode(NodeInterface $node, string $namespace = null)
+    public function dumpNode(NodeInterface $node, ?string $namespace = null)
     {
         $this->reference = '';
         $this->writeNode($node, 0, true, $namespace);
@@ -42,7 +42,7 @@
         return $ref;
     }
 
-    private function writeNode(NodeInterface $node, int $depth = 0, bool $root = false, string $namespace = null)
+    private function writeNode(NodeInterface $node, int $depth = 0, bool $root = false, ?string $namespace = null)
     {
         $rootName = ($root ? 'config' : $node->getName());
         $rootNamespace = ($namespace ?: ($root ? 'http://example.org/schema/dic/'.$node->getName() : null));
diff -ruN a/Definition/Dumper/YamlReferenceDumper.php b/Definition/Dumper/YamlReferenceDumper.php
--- a/Definition/Dumper/YamlReferenceDumper.php	2026-07-15 12:28:18
+++ b/Definition/Dumper/YamlReferenceDumper.php	2026-07-15 12:28:18
@@ -71,7 +71,7 @@
         return $ref;
     }
 
-    private function writeNode(NodeInterface $node, NodeInterface $parentNode = null, int $depth = 0, bool $prototypedArray = false)
+    private function writeNode(NodeInterface $node, ?NodeInterface $parentNode = null, int $depth = 0, bool $prototypedArray = false)
     {
         $comments = [];
         $default = '';
diff -ruN a/Definition/EnumNode.php b/Definition/EnumNode.php
--- a/Definition/EnumNode.php	2026-07-15 12:28:18
+++ b/Definition/EnumNode.php	2026-07-15 12:28:18
@@ -22,7 +22,7 @@
 {
     private array $values;
 
-    public function __construct(?string $name, NodeInterface $parent = null, array $values = [], string $pathSeparator = BaseNode::DEFAULT_PATH_SEPARATOR)
+    public function __construct(?string $name, ?NodeInterface $parent = null, array $values = [], string $pathSeparator = BaseNode::DEFAULT_PATH_SEPARATOR)
     {
         $values = array_unique($values);
         if (empty($values)) {
diff -ruN a/Definition/NumericNode.php b/Definition/NumericNode.php
--- a/Definition/NumericNode.php	2026-07-15 12:28:18
+++ b/Definition/NumericNode.php	2026-07-15 12:28:18
@@ -23,7 +23,7 @@
     protected $min;
     protected $max;
 
-    public function __construct(?string $name, NodeInterface $parent = null, int|float $min = null, int|float $max = null, string $pathSeparator = BaseNode::DEFAULT_PATH_SEPARATOR)
+    public function __construct(?string $name, ?NodeInterface $parent = null, int|float|null $min = null, int|float|null $max = null, string $pathSeparator = BaseNode::DEFAULT_PATH_SEPARATOR)
     {
         parent::__construct($name, $parent, $pathSeparator);
         $this->min = $min;
diff -ruN a/Definition/Processor.php b/Definition/Processor.php
--- a/Definition/Processor.php	2026-07-15 12:28:18
+++ b/Definition/Processor.php	2026-07-15 12:28:18
@@ -67,7 +67,7 @@
      * @param string $key    The key to normalize
      * @param string $plural The plural form of the key if it is irregular
      */
-    public static function normalizeConfig(array $config, string $key, string $plural = null): array
+    public static function normalizeConfig(array $config, string $key, ?string $plural = null): array
     {
         if (null === $plural) {
             $plural = $key.'s';
diff -ruN a/Exception/FileLoaderImportCircularReferenceException.php b/Exception/FileLoaderImportCircularReferenceException.php
--- a/Exception/FileLoaderImportCircularReferenceException.php	2026-07-15 12:28:18
+++ b/Exception/FileLoaderImportCircularReferenceException.php	2026-07-15 12:28:18
@@ -18,7 +18,7 @@
  */
 class FileLoaderImportCircularReferenceException extends LoaderLoadException
 {
-    public function __construct(array $resources, int $code = 0, \Throwable $previous = null)
+    public function __construct(array $resources, int $code = 0, ?\Throwable $previous = null)
     {
         $message = sprintf('Circular reference detected in "%s" ("%s" > "%s").', $this->varToString($resources[0]), implode('" > "', $resources), $resources[0]);
 
diff -ruN a/Exception/FileLocatorFileNotFoundException.php b/Exception/FileLocatorFileNotFoundException.php
--- a/Exception/FileLocatorFileNotFoundException.php	2026-07-15 12:28:18
+++ b/Exception/FileLocatorFileNotFoundException.php	2026-07-15 12:28:18
@@ -20,7 +20,7 @@
 {
     private array $paths;
 
-    public function __construct(string $message = '', int $code = 0, \Throwable $previous = null, array $paths = [])
+    public function __construct(string $message = '', int $code = 0, ?\Throwable $previous = null, array $paths = [])
     {
         parent::__construct($message, $code, $previous);
 
diff -ruN a/Exception/LoaderLoadException.php b/Exception/LoaderLoadException.php
--- a/Exception/LoaderLoadException.php	2026-07-15 12:28:18
+++ b/Exception/LoaderLoadException.php	2026-07-15 12:28:18
@@ -25,7 +25,7 @@
      * @param \Throwable|null $previous       A previous exception
      * @param string|null     $type           The type of resource
      */
-    public function __construct(string $resource, string $sourceResource = null, int $code = 0, \Throwable $previous = null, string $type = null)
+    public function __construct(string $resource, ?string $sourceResource = null, int $code = 0, ?\Throwable $previous = null, ?string $type = null)
     {
         $message = '';
         if ($previous) {
diff -ruN a/FileLocator.php b/FileLocator.php
--- a/FileLocator.php	2026-07-15 12:28:18
+++ b/FileLocator.php	2026-07-15 12:28:18
@@ -33,7 +33,7 @@
     /**
      * {@inheritdoc}
      */
-    public function locate(string $name, string $currentPath = null, bool $first = true)
+    public function locate(string $name, ?string $currentPath = null, bool $first = true)
     {
         if ('' === $name) {
             throw new \InvalidArgumentException('An empty file name is not valid to be located.');
diff -ruN a/FileLocatorInterface.php b/FileLocatorInterface.php
--- a/FileLocatorInterface.php	2026-07-15 12:28:18
+++ b/FileLocatorInterface.php	2026-07-15 12:28:18
@@ -30,5 +30,5 @@
      * @throws \InvalidArgumentException        If $name is empty
      * @throws FileLocatorFileNotFoundException If a file is not found
      */
-    public function locate(string $name, string $currentPath = null, bool $first = true);
+    public function locate(string $name, ?string $currentPath = null, bool $first = true);
 }
diff -ruN a/Loader/DelegatingLoader.php b/Loader/DelegatingLoader.php
--- a/Loader/DelegatingLoader.php	2026-07-15 12:28:18
+++ b/Loader/DelegatingLoader.php	2026-07-15 12:28:18
@@ -31,7 +31,7 @@
     /**
      * {@inheritdoc}
      */
-    public function load(mixed $resource, string $type = null): mixed
+    public function load(mixed $resource, ?string $type = null): mixed
     {
         if (false === $loader = $this->resolver->resolve($resource, $type)) {
             throw new LoaderLoadException($resource, null, 0, null, $type);
@@ -43,7 +43,7 @@
     /**
      * {@inheritdoc}
      */
-    public function supports(mixed $resource, string $type = null): bool
+    public function supports(mixed $resource, ?string $type = null): bool
     {
         return false !== $this->resolver->resolve($resource, $type);
     }
diff -ruN a/Loader/FileLoader.php b/Loader/FileLoader.php
--- a/Loader/FileLoader.php	2026-07-15 12:28:18
+++ b/Loader/FileLoader.php	2026-07-15 12:28:18
@@ -31,7 +31,7 @@
 
     private ?string $currentDir = null;
 
-    public function __construct(FileLocatorInterface $locator, string $env = null)
+    public function __construct(FileLocatorInterface $locator, ?string $env = null)
     {
         $this->locator = $locator;
         parent::__construct($env);
@@ -68,7 +68,7 @@
      * @throws FileLoaderImportCircularReferenceException
      * @throws FileLocatorFileNotFoundException
      */
-    public function import(mixed $resource, string $type = null, bool $ignoreErrors = false, string $sourceResource = null, string|array $exclude = null)
+    public function import(mixed $resource, ?string $type = null, bool $ignoreErrors = false, ?string $sourceResource = null, string|array|null $exclude = null)
     {
         if (\is_string($resource) && \strlen($resource) !== ($i = strcspn($resource, '*?{[')) && !str_contains($resource, "\n")) {
             $excluded = [];
@@ -99,7 +99,7 @@
     /**
      * @internal
      */
-    protected function glob(string $pattern, bool $recursive, array|GlobResource &$resource = null, bool $ignoreErrors = false, bool $forExclusion = false, array $excluded = [])
+    protected function glob(string $pattern, bool $recursive, array|GlobResource|null &$resource = null, bool $ignoreErrors = false, bool $forExclusion = false, array $excluded = [])
     {
         if (\strlen($pattern) === $i = strcspn($pattern, '*?{[')) {
             $prefix = $pattern;
@@ -131,7 +131,7 @@
         yield from $resource;
     }
 
-    private function doImport(mixed $resource, string $type = null, bool $ignoreErrors = false, string $sourceResource = null)
+    private function doImport(mixed $resource, ?string $type = null, bool $ignoreErrors = false, ?string $sourceResource = null)
     {
         try {
             $loader = $this->resolve($resource, $type);
diff -ruN a/Loader/GlobFileLoader.php b/Loader/GlobFileLoader.php
--- a/Loader/GlobFileLoader.php	2026-07-15 12:28:18
+++ b/Loader/GlobFileLoader.php	2026-07-15 12:28:18
@@ -21,7 +21,7 @@
     /**
      * {@inheritdoc}
      */
-    public function load(mixed $resource, string $type = null): mixed
+    public function load(mixed $resource, ?string $type = null): mixed
     {
         return $this->import($resource);
     }
@@ -29,7 +29,7 @@
     /**
      * {@inheritdoc}
      */
-    public function supports(mixed $resource, string $type = null): bool
+    public function supports(mixed $resource, ?string $type = null): bool
     {
         return 'glob' === $type;
     }
diff -ruN a/Loader/Loader.php b/Loader/Loader.php
--- a/Loader/Loader.php	2026-07-15 12:28:18
+++ b/Loader/Loader.php	2026-07-15 12:28:18
@@ -23,7 +23,7 @@
     protected $resolver;
     protected $env;
 
-    public function __construct(string $env = null)
+    public function __construct(?string $env = null)
     {
         $this->env = $env;
     }
@@ -49,7 +49,7 @@
      *
      * @return mixed
      */
-    public function import(mixed $resource, string $type = null)
+    public function import(mixed $resource, ?string $type = null)
     {
         return $this->resolve($resource, $type)->load($resource, $type);
     }
@@ -59,7 +59,7 @@
      *
      * @throws LoaderLoadException If no loader is found
      */
-    public function resolve(mixed $resource, string $type = null): LoaderInterface
+    public function resolve(mixed $resource, ?string $type = null): LoaderInterface
     {
         if ($this->supports($resource, $type)) {
             return $this;
diff -ruN a/Loader/LoaderInterface.php b/Loader/LoaderInterface.php
--- a/Loader/LoaderInterface.php	2026-07-15 12:28:18
+++ b/Loader/LoaderInterface.php	2026-07-15 12:28:18
@@ -25,7 +25,7 @@
      *
      * @throws \Exception If something went wrong
      */
-    public function load(mixed $resource, string $type = null);
+    public function load(mixed $resource, ?string $type = null);
 
     /**
      * Returns whether this class supports the given resource.
@@ -34,7 +34,7 @@
      *
      * @return bool
      */
-    public function supports(mixed $resource, string $type = null);
+    public function supports(mixed $resource, ?string $type = null);
 
     /**
      * Gets the loader resolver.
diff -ruN a/Loader/LoaderResolver.php b/Loader/LoaderResolver.php
--- a/Loader/LoaderResolver.php	2026-07-15 12:28:18
+++ b/Loader/LoaderResolver.php	2026-07-15 12:28:18
@@ -39,7 +39,7 @@
     /**
      * {@inheritdoc}
      */
-    public function resolve(mixed $resource, string $type = null): LoaderInterface|false
+    public function resolve(mixed $resource, ?string $type = null): LoaderInterface|false
     {
         foreach ($this->loaders as $loader) {
             if ($loader->supports($resource, $type)) {
diff -ruN a/Loader/LoaderResolverInterface.php b/Loader/LoaderResolverInterface.php
--- a/Loader/LoaderResolverInterface.php	2026-07-15 12:28:18
+++ b/Loader/LoaderResolverInterface.php	2026-07-15 12:28:18
@@ -23,5 +23,5 @@
      *
      * @param string|null $type The resource type or null if unknown
      */
-    public function resolve(mixed $resource, string $type = null): LoaderInterface|false;
+    public function resolve(mixed $resource, ?string $type = null): LoaderInterface|false;
 }
diff -ruN a/Resource/ClassExistenceResource.php b/Resource/ClassExistenceResource.php
--- a/Resource/ClassExistenceResource.php	2026-07-15 12:28:18
+++ b/Resource/ClassExistenceResource.php	2026-07-15 12:28:18
@@ -34,7 +34,7 @@
      * @param string    $resource The fully-qualified class name
      * @param bool|null $exists   Boolean when the existency check has already been done
      */
-    public function __construct(string $resource, bool $exists = null)
+    public function __construct(string $resource, ?bool $exists = null)
     {
         $this->resource = $resource;
         if (null !== $exists) {
@@ -143,7 +143,7 @@
      *
      * @internal
      */
-    public static function throwOnRequiredClass(string $class, \Exception $previous = null)
+    public static function throwOnRequiredClass(string $class, ?\Exception $previous = null)
     {
         // If the passed class is the resource being checked, we shouldn't throw.
         if (null === $previous && self::$autoloadedClass === $class) {
diff -ruN a/Resource/DirectoryResource.php b/Resource/DirectoryResource.php
--- a/Resource/DirectoryResource.php	2026-07-15 12:28:18
+++ b/Resource/DirectoryResource.php	2026-07-15 12:28:18
@@ -29,7 +29,7 @@
      *
      * @throws \InvalidArgumentException
      */
-    public function __construct(string $resource, string $pattern = null)
+    public function __construct(string $resource, ?string $pattern = null)
     {
         $resolvedResource = realpath($resource) ?: (file_exists($resource) ? $resource : false);
         $this->pattern = $pattern;
diff -ruN a/ResourceCheckerConfigCache.php b/ResourceCheckerConfigCache.php
--- a/ResourceCheckerConfigCache.php	2026-07-15 12:28:18
+++ b/ResourceCheckerConfigCache.php	2026-07-15 12:28:18
@@ -110,7 +110,7 @@
      *
      * @throws \RuntimeException When cache file can't be written
      */
-    public function write(string $content, array $metadata = null)
+    public function write(string $content, ?array $metadata = null)
     {
         $mode = 0666;
         $umask = umask();
diff -ruN a/Util/XmlUtils.php b/Util/XmlUtils.php
--- a/Util/XmlUtils.php	2026-07-15 12:28:18
+++ b/Util/XmlUtils.php	2026-07-15 12:28:18
@@ -42,7 +42,7 @@
      * @throws InvalidXmlException When parsing of XML with schema or callable produces any errors unrelated to the XML parsing itself
      * @throws \RuntimeException   When DOM extension is missing
      */
-    public static function parse(string $content, string|callable $schemaOrCallable = null): \DOMDocument
+    public static function parse(string $content, string|callable|null $schemaOrCallable = null): \DOMDocument
     {
         if (!\extension_loaded('dom')) {
             throw new \LogicException('Extension DOM is required.');
@@ -112,7 +112,7 @@
      * @throws XmlParsingException       When XML parsing returns any errors
      * @throws \RuntimeException         When DOM extension is missing
      */
-    public static function loadFile(string $file, string|callable $schemaOrCallable = null): \DOMDocument
+    public static function loadFile(string $file, string|callable|null $schemaOrCallable = null): \DOMDocument
     {
         if (!is_file($file)) {
             throw new \InvalidArgumentException(sprintf('Resource "%s" is not a file.', $file));