fullFileExtension property
The full file extension; extracted from the title.
May contain multiple concatenated extensions, such as "tar.gz". Removing an extension from the title does not clear this field; however, changing the extension on the title does update this field. This field is only populated for files with content stored in Google Drive; it is not populated for Docs Editors or shortcut files.
Output only.
Implementation
core.String? fullFileExtension;