protected void initMap() throws IOException {
        for (Enumeration<? extends ZipEntry> e = zfile.entries(); e.hasMoreElements(); ) {
            ZipEntry entry;
            try {
                entry = e.nextElement();
            } catch (InternalError ex) {
                IOException io = new IOException();
                io.initCause(ex); // convenience constructors added in Mustang :-(
                throw io;
            }
            addZipEntry(entry);
        }
    }