public static String next() {
        return "attach" + counter.incrementAndGet();
    }
@Test
    public void next() {
        AttachName.reset();
        assertEquals("attach1", AttachName.next());
        assertEquals("attach2", AttachName.next());
        assertEquals("attach3", AttachName.next());
        assertEquals("attach4", AttachName.next());
        assertEquals("attach5", AttachName.next());
    }