[xwiki-devs] [proposal] New way to make sure temp files are deleted.

Hi, In order to fix XWIKI-7748 and XWIKI-7749, we need a plan for deleting temporary file. XWikiAttachmentContent uses File.deleteOnExit(), but in Sun's implementation, deleteOnExit() only deletes on a *clean* exit, in a crash it can't delete the files but it doesn't tag them so they can be deleted in the next run either. Since temp files are usually pseudo-randomly named, they are impossible to find and delete later. I propose that we create a subdirectory, `java.io.tmpdir`/xwiki/ which will be removed on application exit. If the jvm crashes, the files will be removed next time around. Then alter ApplicationContext.getTemporaryDirectory() to yield this directory. WDYT? Caleb