void assertHeaderValue(final LoggedRequest loggedRequest,
                           final String key,
                           final String value) {
        Assertions.assertThat(loggedRequest.getHeader(key))
                .isNotNull()
                .isEqualTo(value);
    }
Assert that a http header is present and has this value
stroom-proxy/stroom-proxy-app/src/test/java/stroom/proxy/app/MockHttpDestination.java