@Override
    // not used in the codebase, here just for future API usage
    public boolean isEmpty() {
        return size() == 0;
    }
@Test
    public void testIsEmpty() {
        final ArrayRingbuffer<String> rb = new ArrayRingbuffer<>(5);
        assertTrue(rb.isEmpty());
        rb.add("");
        assertFalse(rb.isEmpty());
    }