bug symfony#44745 [EventDispatcher][HttpFoundation] Restore return ty…

…pe to covariant IteratorAggregate implementations (derrabus)

This PR was merged into the 6.0 branch.

Discussion
----------

[EventDispatcher][HttpFoundation] Restore return type to covariant IteratorAggregate implementations

| Q             | A
| ------------- | ---
| Branch?       | 6.0
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | Follows symfony#44731
| License       | MIT
| Doc PR        | N/A

Commits
-------

0f2b5bb Restore return type to covariant IteratorAggregate implementations

src/Symfony/Component/EventDispatcher/GenericEvent.php

@@ -148,6 +148,8 @@ public function offsetExists(mixed $key): bool
 
     /**
      * IteratorAggregate for iterating over the object like an array.
+     *
+     * @return \ArrayIterator<string, mixed>
      */
     public function getIterator(): \ArrayIterator
     {

src/Symfony/Component/HttpFoundation/HeaderBag.php

@@ -238,6 +238,8 @@ public function removeCacheControlDirective(string $key)
 
     /**
      * Returns an iterator for headers.
+     *
+     * @return \ArrayIterator<string, list<string|null>>
      */
     public function getIterator(): \ArrayIterator
     {

src/Symfony/Component/HttpFoundation/ParameterBag.php

@@ -171,6 +171,8 @@ public function filter(string $key, mixed $default = null, int $filter = \FILTER
 
     /**
      * Returns an iterator for parameters.
+     *
+     * @return \ArrayIterator<string, mixed>
      */
     public function getIterator(): \ArrayIterator
     {

src/Symfony/Component/HttpFoundation/Session/Attribute/AttributeBag.php

@@ -130,6 +130,8 @@ public function clear(): mixed
 
     /**
      * Returns an iterator for attributes.
+     *
+     * @return \ArrayIterator<string, mixed>
      */
     public function getIterator(): \ArrayIterator
     {

src/Symfony/Component/HttpFoundation/Session/Session.php

@@ -128,6 +128,8 @@ public function isStarted(): bool
 
     /**
      * Returns an iterator for attributes.
+     *
+     * @return \ArrayIterator<string, mixed>
      */
     public function getIterator(): \ArrayIterator
     {