FileName Variable in Run Time Prompts

I have an integration rule in the data exchange for importing a data file, and associated with it, I have a business rule (Groovy) set to run on the "Before Import" event.

This business rule is used to validate the file name to ensure it matches the correct rule.

To identify the Run Time Prompts in the Integration Rule menu, how can I reference the FileName variable?

I set up the run time prompt "FileNome" as "Custom" in Value Time and in Custom Value i tried to write: §FileName§; §FileName; FileName; in blank…