This is a java problem not an MS one... but anyway.. you could put a delete batch file in the startup group for each user that deletes that users cache if deleting it doesn't cause problems- below is an example name it delfiles.bat or something and put it in the all users stat menu start up folder.. example below set to whatever path you want and each time a user logs in it will clear theirs.
@ECHO OFF
DEL "%USERPROFILE%\app data\whatever path\*.*" /Y /S