protected function getCollection(EnvironmentInterface $environment)
    {
        $dataDefinition = $environment->getDataDefinition();
        $relationShip   = $dataDefinition->getModelRelationshipDefinition();

        if (!$relationShip->getChildCondition($dataDefinition->getName(), $dataDefinition->getName())) {
            return $this->getFlatCollection($environment);
        }

        return $this->getHierarchyCollection($this->getClipboardItems($environment), $environment);
    }