public long contentSize()
    {
        long size = 0;
        for (ZFrame f : frames) {
            size += f.size();
        }
        return size;
    }
@Test
    public void testContentSize()
    {
        ZMsg msg = new ZMsg();

        msg.add(new byte[0]);
        assertThat(msg.contentSize(), is(0L));

        msg.add(new byte[1]);
        assertThat(msg.contentSize(), is(1L));
    }