ApiPlatform\Core\Bridge\Symfony\Bundle\DependencyInjection\Configuration::addFormatSection PHP Method

    private function addFormatSection(ArrayNodeDefinition $rootNode, string $key, array $defaultValue)
    {
        $rootNode->children()->arrayNode($key)->defaultValue($defaultValue)->info('The list of enabled formats. The first one will be the default.')->normalizeKeys(false)->useAttributeAsKey('format')->beforeNormalization()->ifArray()->then(function ($v) {
            foreach ($v as $format => $value) {
                if (isset($value['mime_types'])) {
                    continue;
                }
                $v[$format] = ['mime_types' => $value];
            }
            return $v;
        })->end()->prototype('array')->children()->arrayNode('mime_types')->prototype('scalar')->end()->end()->end()->end()->end()->end();
    }