Currently, in the fileDownloadOperation in file-operations-plugin, the targetFileName is required.

Instead, if the targetFileName is empty, the targetFileName should default to the filename parameter of the Content-Disposition header, or if not present, the filename following the last / in the URL.

I can provide a pull request if that helps. Also, the 'file-operations-plugin' JIRA component is missing, so I chose 'plugin-proposals' as the component. Can someone with permissions create the 'file-operations-plugin' component and edit this issue please?