I don't know what file.isFile() api your talking about, VirtualFile or java.io.File. So looking for this statement in the vfs codebase, I find it in FileSystemContext.createVirtualFileHandler. and there it is java.io.File.isFile(). So for that usage, yes, we know whether its an unpacked jar or not. For that IOException, I don't know why we fall back to treating the corrupt jar as a non-structured file. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4135665#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...