feat(symfony): Deprecate resource_class_directories config

Author: GromNaN

src/Symfony/Bundle/DependencyInjection/ApiPlatformExtension.php

@@ -171,8 +171,9 @@ public function load(array $configs, ContainerBuilder $container): void
         $container->registerForAutoconfiguration(ParameterProviderInterface::class)
             ->addTag('api_platform.parameter_provider');
         $container->registerAttributeForAutoconfiguration(ApiResource::class, static function (ChildDefinition $definition): void {
-            $definition->addTag('api_platform.resource');
-            $definition->addTag('container.excluded', ['source' => __FILE__]);
+            $definition->setAbstract(true)
+                ->addTag('api_platform.resource')
+                ->addTag('container.excluded', ['source' => 'by #[ApiResource] attribute']);
         });
 
         if (!$container->has('api_platform.state.item_provider')) {

src/Symfony/Bundle/DependencyInjection/Configuration.php

@@ -141,6 +141,7 @@ public function getConfigTreeBuilder(): TreeBuilder
                 ->end()
                 ->arrayNode('resource_class_directories')
                     ->prototype('scalar')->end()
+                    ->setDeprecated('api-platform/symfony', '4.1', 'The "resource_class_directories" configuration is deprecated, classes using #[ApiResource] attribute are autoconfigured by the dependency injection container.')
                 ->end()
                 ->arrayNode('serializer')
                     ->addDefaultsIfNotSet()