public function associateCompetencyToResources(Competency $competency, array $nodes)
    {
        $associatedNodes = [];

        foreach ($nodes as $node) {
            if (!$competency->isLinkedToResource($node)) {
                $competency->linkResource($node);
                $associatedNodes[] = $node;
            }
        }
        $this->om->persist($competency);
        $this->om->flush();

        return $associatedNodes;
    }