@Override
    public Map<String, String> contextLabels() {
        return Collections.unmodifiableMap(contextLabels);
    }
@Test
    public void testKafkaMetricsContextLabelsAreImmutable() {
        context = new KafkaMetricsContext(namespace, labels);
        assertThrows(UnsupportedOperationException.class, () -> context.contextLabels().clear());
    }