Sound cache problem

I have seen, on the Spoutcraft Documentation, the custom music can be cached for future use, and be saved for the next Spoutcraft launch.
http://spoutcraft.github.io/SpoutcraftPlugin/org/getspout/spout/sound/SimpleSoundManager.htm

But, when I try it, I got some problem on the caching system:
If "plugin" refer to null, the downloaded songs will go on:
C:\Users\***\AppData\Roaming\.technic\modpacks\spoutcraft\cache\temp\temp\Song.mp3
instead of:
C:\Users\***\AppData\Roaming\.technic\modpacks\spoutcraft\cache\temp\Song.mp3

If "plugin" refer to the actual plugin, the downloaded songs will go on:
C:\Users\***\AppData\Roaming\.technic\modpacks\spoutcraft\cache\temp\PluginName\Song.mp3
instead of:
 C:\Users\***\AppData\Roaming\.technic\modpacks\spoutcraft\cache\PluginName\Song.mp3

Both of the files will go on the \temp folder, but the temp folder was deleted after every Spoutcraft restart.
I hope you can fix it quickly, 
splint33