models/classes/creator/TreeItemLookup.php
public function getItems(\core_kernel_classes_Class $itemClass, array $propertyFilters = [], $offset = 0, $limit = 30)
    {
        $data =  $this->getTreeResourceLookupService()->getResources($itemClass, [], $propertyFilters, $offset, $limit);
        return $this->formatTreeData($data);
    }
public function getItems(\core_kernel_classes_Class $itemClass, array $propertyFilters = [], $offset = 0, $limit = 30)
    {
        $data =  $this->getTreeResourceLookupService()->getResources($itemClass, [], $propertyFilters, $offset, $limit);
        return $this->formatTreeData($data);
    }
Retrieve QTI Items in their hierarchy, for the given parameters as format them as tree.
@param \core_kernel_classes_Class $itemClass the item class
@param array $propertyFilters propUri/propValue to search items
@param int    $offset for paging
@param int    $limit  for paging
@return array the items