@Override
    public Mono<ObjectNode> fetchReceiverConfig(String notifierDescriptorName) {
        return fetchConfig(notifierDescriptorName)
            .mapNotNull(setting -> (ObjectNode) setting.get(RECEIVER_KEY))
            .defaultIfEmpty(JsonNodeFactory.instance.objectNode());
    }
@Test
    void fetchReceiverConfigTest() {
        var objectNode = mock(ObjectNode.class);
        var spyNotifierConfigStore = spy(notifierConfigStore);

        doReturn(Mono.just(objectNode)).when(spyNotifierConfigStore)
            .fetchConfig(eq("fake-notifier"));
        var receiverConfig = mock(ObjectNode.class);
        when(objectNode.get(eq(RECEIVER_KEY))).thenReturn(receiverConfig);

        spyNotifierConfigStore.fetchReceiverConfig("fake-notifier")
            .as(StepVerifier::create)
            .consumeNextWith(actual -> assertThat(actual).isEqualTo(receiverConfig))
            .verifyComplete();
        verify(objectNode).get(eq(RECEIVER_KEY));
    }