@Test
    @Configuration(classpathConfigFile = "response-header-config.json")
    @BackEndApi(EchoBackEndApi.class)
    public void testResponseHeaderSet() throws Throwable {
        final PolicyTestRequest request = PolicyTestRequest.build(PolicyTestRequestType.GET, "/example");
        final PolicyTestResponse response = send(request);

        assertEquals(HttpURLConnection.HTTP_OK, response.code());
        assertNotNull(response.body());

        final Map<String, String> headers = response.headers().toMap();
        assertNotNull(headers);
        assertNotNull(headers.get(HEADER_NAME));
    }
Expects that a unique value is set in the response with the HTTP Header name 'X-CorrelationID'.
plugins/unique-header-policy/src/test/java/io/apiman/plugins/uniqueheader/UniqueHeaderPolicyTest.java