Merge branch '5.4' into 6.2

* 5.4: relax assertions for ICU 72.1 [Validator] Fix regression with class metadatada on parent classes [VarExporter] Fix exporting classes with __serialize() but not __unserialize() [HttpFoundation][HttpKernel] Fix deprecations when `Content-Type` is `null`

Author: derrabus

Response.php

@@ -281,7 +281,7 @@ public function prepare(Request $request): static
  $charset = $this->charset ?: 'UTF-8';
  if (!$headers->has('Content-Type')) {
  $headers->set('Content-Type', 'text/html; charset='.$charset);
- } elseif (0 === stripos($headers->get('Content-Type'), 'text/') && false === stripos($headers->get('Content-Type'), 'charset')) {
+ } elseif (0 === stripos($headers->get('Content-Type') ?? '', 'text/') && false === stripos($headers->get('Content-Type') ?? '', 'charset')) {
  // add the charset
  $headers->set('Content-Type', $headers->get('Content-Type').'; charset='.$charset);
  }

Tests/ResponseTest.php

@@ -537,6 +537,16 @@ public function testContentTypeCharset()
  $this->assertEquals('text/css; charset=UTF-8', $response->headers->get('Content-Type'));
  }
 
+ public function testContentTypeIsNull()
+ {
+ $response = new Response('foo');
+ $response->headers->set('Content-Type', null);
+
+ $response->prepare(new Request());
+
+ $this->expectNotToPerformAssertions();
+ }
+
  public function testPrepareDoesNothingIfContentTypeIsSet()
  {
  $response = new Response('foo');