private function getMetadataProperties()
    {
        $triples = $this->getResource()->getRdfTriples();
        $properties = [];
        foreach ($triples as $triple){
            $properties[$triple->predicate] = $triple->object;
        }
        //we also include a shortcut to the item URI
        $properties['@uri'] = $this->getResource()->getUri();
        return $properties;
    }