Tibco (Jaspersoft) do not have the XML Export as a standard functionality. They have a default JR XML Exporter class as below which you have also found:
but this will output to a proprietary XML structure format which may not be the structure you want.
Hence you have to write your own custom XML exporter to produce your own XML output.
Additional Information
There is a section on XML Exporter in the JasperReports Library Ultimate Guide (page 258) that you can refer to. This document can be downloaded from the community docs section here: