private static function getGlobalConfig(Composer $composer, $filename, $io = null)
    {
        $home = self::getComposerHome($composer);
        $file = new JsonFile($home.'/'.$filename.'.json');
        $config = array();

        if ($file->exists()) {
            $data = $file->read();

            if (isset($data['config']['fxp-asset']) && \is_array($data['config']['fxp-asset'])) {
                $config = $data['config']['fxp-asset'];

                if ($io instanceof IOInterface && $io->isDebug()) {
                    $io->writeError('Loading fxp-asset config in file '.$file->getPath());
                }
            }
        }

        return $config;
    }