$node = Node::create(['type' => 'my_contentType']);
$node->set('title', $item['name']);
$node->set('field_author_name', $item['author']);
foreach ($FilePaths_keys as $path){
$digitalFile_path = $item['bitstreams'][$path] ['retrieveLink'];
$get_data_contents = file_get_contents($digitalFile_path);
$file = file_save_data($get_data_contents, 'public://'.$item['bitstreams'][$path]['name'], FILE_EXISTS_REPLACE);
$Dfiles = [
        'target_id' => $file->id(),
        'alt' => $item['bitstreams'][$path]['name'],
        'title' => $item['bitstreams'][$path]['name']
      ];
$node->set('field_book_image', $Dfiles);
}
$node->enforceIsNew();
$node->save();