public static function primaryNamespace($package)
    {
        $primaryNs = null;
        $autoLoad = $package->getAutoload();
        foreach ($autoLoad as $type => $pathMap) {
            if ($type !== 'psr-4') {
                continue;
            }
            $count = count($pathMap);

            if ($count === 1) {
                $primaryNs = key($pathMap);
                break;
            }

            $matches = preg_grep('#^(\./)?src/?$#', $pathMap);
            if ($matches) {
                $primaryNs = key($matches);
                break;
            }

            foreach (['', '.'] as $path) {
                $key = array_search($path, $pathMap, true);
                if ($key !== false) {
                    $primaryNs = $key;
                }
            }
            break;
        }

        if (!$primaryNs) {
            throw new RuntimeException(
                sprintf(
                    "Unable to get primary namespace for package %s." .
                    "\nEnsure you have added proper 'autoload' section to your plugin's config.",
                    $package->getName()
                )
            );
        }
        return trim($primaryNs, '\\');
    }