In "older" freestyle-jobs the file-pattern is still used, but with the current xUnit-release 2.3.5 this parameter is no longer shown nor can be changed. Within the raw XML-config-file of these older jobs the XML-item beginns with <xunit plugin="xunit@2.3.3"> and have still have an pattern-entry.

See attached sreenshot (screen-xunit.jpg) showing the current presentation of this post-build action ...

Best regards from Salzburg, Markus