bug symfony#58255 [Serializer] Fix ObjectNormalizer gives warnings on normalizing with public static property (André Laugks)

This PR was submitted for the 7.1 branch but it was squashed and merged into the 6.4 branch instead.

Discussion
----------

[Serializer] Fix `ObjectNormalizer` gives warnings on normalizing with public static property

| Q             | A           |
|---------------|-------------|
| Branch?       | 6.4 |
| Bug fix?      | yes         |
| New feature?  | no          |
| Deprecations? | no          |
| Issues        | Fix symfony#58221  |
| License       | MIT         |

The error message has been occurring since version 6.4.11/7.1.2. If the condition is changed to version >=7.1.2, the error message no longer occurs.

The error is thrown with the following ObjectNormalizer configuration:

```php
$class = new class {
    public static string $foo = "hallo";
};

$normalizer = new ObjectNormalizer(new ClassMetadataFactory(new AttributeLoader()));
$normalizer->normalize($class);
```

`(\is_object($classOrObject) && $this->propertyAccessor->isReadable($classOrObject, $attribute))` is true and therefore the entire condition is true.

I moved the condition into a method to improve readability and reduce complexity.

All serializer tests are successful.

### Condition

For better readability here with breaks.

**7.1.1**
https://github.com/symfony/symfony/blob/v7.1.1/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php#L180
```php
if (!isset(self::$isReadableCache[$class.$attribute])) {
    self::$isReadableCache[$class.$attribute] =
    $this->propertyInfoExtractor->isReadable($class, $attribute)
    || $this->hasAttributeAccessorMethod($class, $attribute);
}
```

**>=7.2.2**
https://github.com/symfony/symfony/blob/v7.1.2/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php#L180
```php
if (!isset(self::$isReadableCache[$class.$attribute])) {
    self::$isReadableCache[$class.$attribute] =
    (\is_object($classOrObject) && $this->propertyAccessor->isReadable($classOrObject, $attribute))
    || $this->propertyInfoExtractor->isReadable($class, $attribute)
    || $this->hasAttributeAccessorMethod($class, $attribute);
}
```

**Fixed condition**
```php
if (!isset(self::$isReadableCache[$class.$attribute])) {
    self::$isReadableCache[$class.$attribute] =
    $this->propertyInfoExtractor->isReadable($class, $attribute)
    || $this->hasAttributeAccessorMethod($class, $attribute)
    || (\is_object($classOrObject) && $this->propertyAccessor->isReadable($classOrObject, $attribute));
}
```

Commits
-------

bcc38d9 [Serializer] Fix `ObjectNormalizer` gives warnings on normalizing with public static property

Author: nicolas-grekas

src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php

@@ -197,7 +197,7 @@ protected function isAllowedAttribute($classOrObject, string $attribute, ?string
 
         if ($context['_read_attributes'] ?? true) {
             if (!isset(self::$isReadableCache[$class.$attribute])) {
-                self::$isReadableCache[$class.$attribute] = (\is_object($classOrObject) && $this->propertyAccessor->isReadable($classOrObject, $attribute)) || $this->propertyInfoExtractor->isReadable($class, $attribute) || $this->hasAttributeAccessorMethod($class, $attribute);
+                self::$isReadableCache[$class.$attribute] = $this->propertyInfoExtractor->isReadable($class, $attribute) || $this->hasAttributeAccessorMethod($class, $attribute) || (\is_object($classOrObject) && $this->propertyAccessor->isReadable($classOrObject, $attribute));
             }
 
             return self::$isReadableCache[$class.$attribute];

src/Symfony/Component/Serializer/Tests/Normalizer/ObjectNormalizerTest.php

@@ -927,6 +927,16 @@ public function testDenormalizeWithPropertyPath()
 
         $this->assertEquals($expected, $obj);
     }
+
+    public function testObjectNormalizerWithAttributeLoaderAndObjectHasStaticProperty()
+    {
+        $class = new class {
+            public static string $foo;
+        };
+
+        $normalizer = new ObjectNormalizer(new ClassMetadataFactory(new AttributeLoader()));
+        $this->assertSame([], $normalizer->normalize($class));
+    }
 }
 
 class ProxyObjectDummy extends ObjectDummy