Improve the Workflow post-function file extension settings

Currently, using the Parameters of the Xporter for JIRA Create Document Post Function Function screen of a transition, even after selecting the Output Format of the generated document, it is necessary to manually include the file extension while inputting the filename, otherwise, if the fields are filled like on screenshot-1 the generated documents will appear like the ones from screenshot-2 (attached to the issue) and screenshot-3 (saved on the user defined path), despite on the example of screenshot-1 the output format is set to PDF.
But if the fields are filled like on screenshot-4 the generated documents will appear correclty as can be seen on screenshot-5 (attached to the issue) and screenshot-6 (saved on the user define path.

This behaviour should be improved so, when selecting the output format on the Parameters of the Xporter for JIRA Create Document Post Function Function screen, that extension should be automatically associated to the user defined filenames, instead of needing to be manually inputed