public void generateAcknowledgementPayload(
            MllpSocketBuffer mllpSocketBuffer, byte[] hl7MessageBytes, String acknowledgementCode)
            throws MllpAcknowledgementGenerationException {
        generateAcknowledgementPayload(mllpSocketBuffer, hl7MessageBytes, acknowledgementCode, null);
    }
@Test
    public void testGenerateAcknowledgementPayloadTimestamp() throws Exception {
        MllpSocketBuffer mllpSocketBuffer = new MllpSocketBuffer(new MllpEndpointStub());
        hl7util.generateAcknowledgementPayload(mllpSocketBuffer, TEST_MESSAGE.getBytes(), "AA");

        String actualMsh7Field = mllpSocketBuffer.toString().split("\\|")[6];

        assertThat(actualMsh7Field, matchesPattern("\\d{14}\\.\\d{3}[+-]\\d{4}"));
    }