public AckExpression() {
        this((AcknowledgmentCode) null, null, ErrorCode.APPLICATION_INTERNAL_ERROR);
    }
@Test
    public void testAckExpression() throws Exception {
        ADT_A01 a01 = createADT01Message();
        ACK ack = template.requestBody("direct:test1", a01, ACK.class);
        assertEquals("AA", ack.getMSA().getAcknowledgementCode().getValue());
        assertEquals(a01.getMSH().getMessageControlID().getValue(), ack.getMSA().getMessageControlID()
                .getValue());
    }