private function calculateClipboardItems()
    {
        $dataDefinition  = $this->environment->getDataDefinition();
        $basicDefinition = $dataDefinition->getBasicDefinition();
        $clipboard       = $this->environment->getClipboard();

        $filter = new Filter();
        $filter->andModelIsFromProvider($basicDefinition->getDataProvider());
        if ($parentDataProviderName = $basicDefinition->getParentDataProvider()) {
            $filter->andParentIsFromProvider($parentDataProviderName);
        } else {
            $filter->andHasNoParent();
        }

        return $clipboard->fetch($filter);
    }