The package name would be the name of the map file itself. (Either testmap.umap or in engine testmap.testmap); The short package name is just the name of the file (testmap.testmap), the long package name is the full path to the map (Game/Maps/testmap.map)
The bit of code you posted is just printing an error if it cannot find the specified map file.
That being said, I can’t get the conversion to work either. :\