    @Test
    public void testUpdateWithNoConfigReturnsEmptyMap() {

        MultivaluedMap<String, String> incomingHeaders = mockIncomingHeaders();
        MultivaluedMap<String, String> clientOutgoingHeaders = new MultivaluedHashMap<>();
        MultivaluedMap<String, String> updatedHeaders = impl.update(incomingHeaders, clientOutgoingHeaders);
        assertNotNull(updatedHeaders);
        assertEquals(updatedHeaders.size(), 0);
    }