DependencyInjection/FormsExtension.php
private static function mergeFormsConfig(array $configs): array
    {
        $configs = array_reverse($configs);
        $config = [];
        foreach ($configs as $subConfig) {
            $config = array_merge($config, $subConfig);
        }

        return $config;
    }
private static function mergeFormsConfig(array $configs): array
    {
        $configs = array_reverse($configs);
        $config = [];
        foreach ($configs as $subConfig) {
            $config = array_merge($config, $subConfig);
        }

        return $config;
    }
Merge all forms configs in reverse order.
First (user defined) config is most important.

@param array $configs

@return array