Default configuration value is ignored if same parent block exists at resource level.

[acirulis]

API Platform version(s) affected: 2.6.8

Description and steps to reproduce
If "defaults" section in configuration file (config/packages/api_platform.yaml) contains block with some default child parameter and value, for example:

    defaults:
        denormalization_context:
            allow_extra_attributes: false

And Resource level configuration has denormalization_context block with different keys:

ApiResource(
        denormalizationContext: [
            'groups' => ['person_write'],
        ],

Then allow_extra_attributes gets ignored because in AnnotationResourceMetadataFactory.php:95 only existance of parent key is checked, not child values:

private function createMetadata(ApiResource $annotation, ResourceMetadata $parentResourceMetadata = null): ResourceMetadata
    {
        $attributes = null;
        if (null !== $annotation->attributes || [] !== $this->defaults['attributes']) {
            $attributes = (array) $annotation->attributes;
            foreach ($this->defaults['attributes'] as $key => $value) {
                if (!isset($attributes[$key])) {
                    $attributes[$key] = $value;
                }
            }
        }
...

Possible Solution
Must check existence of child keys recursively before skipping default config value.