public static function getPropertyHelper(Project $project)
    {
        /**
         * @var PropertyHelper $helper
         */
        $helper = $project->getReference('phing.PropertyHelper');
        if ($helper !== null) {
            return $helper;
        }
        $helper = new self();
        $helper->setProject($project);

        $project->addReference('phing.PropertyHelper', $helper);
        return $helper;
    }