private Map<String, String> filterMdc(Map<String, String> mdcPropertyMap) {
        if (includesMdcKeys.isEmpty()) {
            return mdcPropertyMap;
        }
        return mdcPropertyMap.entrySet()
            .stream()
            .filter(e -> includesMdcKeys.contains(e.getKey()))
            .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
    }
@Test
    void testFilterMdc() {
        final Set<String> includesMdcKeys = Set.of("userId", "orderId");
        Map<String, Object> map = new EventJsonLayout(jsonFormatter, timestampFormatter, throwableProxyConverter, DEFAULT_EVENT_ATTRIBUTES,
            Collections.emptyMap(), Collections.emptyMap(), includesMdcKeys, false)
                .toJsonMap(event);

        final Map<String, String> expectedMdc = Map.of(
                "userId", "18",
                "orderId", "24");
        final HashMap<String, Object> expectedFields = new HashMap<>(defaultExpectedFields);
        expectedFields.put("mdc", expectedMdc);
        assertThat(map).isEqualTo(expectedFields);
    }