/**
  * Returns document object
  *
  * @param string $documentName
  * @return \Migration\ResourceModel\Structure
  */
 public function getStructure($documentName)
 {
     $data = $this->adapter->getDocumentStructure($this->addDocumentPrefix($documentName));
     return $this->structureFactory->create(['documentName' => $documentName, 'data' => $data]);
 }